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In two-year field experiments, nitrogen (N) in the form of urea (0, 120 and 240 kg N/ha) was applied to grain maize (Zea mays L.) hybrid KWS 2376. The two-year mean content of total grain N at harvest was 1.54%. The highest N dose reduced most of the 17 amino acids (AA) analysed in the grain compared with the other treatments. Possible reasons for this could be an adverse effect on the tricarboxylic acid cycle or deficiency of carbon skeletons for the assimilation of NH4+ into amides and amino acids. The content of the limiting amino acid lysine was not influenced by N fertilisation, with a mean two-year content of 2.02 mg/g DM. Taking into account the differences in fertilisation, the effect of the year was seen in the maximal accumulation of amino acids serine, proline, methionine, threonine, arginine and lysine. Increasing rates of nitrogen reduced the accumulation of asparagine and glycine, and, on the contrary, increased the accumulation of tyrosine. Nitrogen rates have a significant effect on the maximal accumulation of valine, isoleucine, leucine, phenylalanine, histidine, cysteine and alanine and appeared as early as after the first increased rate of nitrogen (120 kg N/ha).

In recent years consumers tend to pay ever greater attention to food ingredients looking for foods with favourable compositional characteristics. Researches nowadays aim to find out what role the different vegetable species play in protection of the human organism. Consumption of vegetables and fruits more times a day plays an important role in this process. The valuable chemical components in plants can eventually be influenced, besides, by environmental characteristics, also by the elements of the production technology applied. Our work aimed to find out what eventual changes occur in the composition parameters of sweet corn (Zea mays convar saccharata Koern.) receiving different NPK fertilizations and top dressed with foliar application of Zn and Mg, destined chiefly for fresh consumption, in response to the treatments mentioned above. The fertiliser rates were compared with the help of the variety Spirit (normal sweet, very early ripening).

In our trial we tried to find out how the time of propagation and transplanting influenced the growing season of sweet corn along with some major properties relevant to quality. The following technological variations were compared with the help of the variety Spirit (normal sweet, very early ripening): transplanted plants with floating row cover (with 2 planting dates); transplanted plants with no row cover: direct seeded plants with no row cover. The 21 day transplant growing period reduced the growing period by 16 to 20 days, compared to the technology used in the existing practice of production. Earliness had a negative influence on ear size, nonetheless it is worth while to attempt since the market is not so exacting with new products in the early period. Covering the seedlings in the early season was clearly beneficial, as the floating row cover provided protection for plants against lower night temperatures which are common in this period.

Investigations into root strength have assumed particular importance with the emergence of American rootworm (Diabrotica virgifera-virgifera) as the number one pest, mainly as a result of monocultural production. Three treatments were applied in the trial: zero control treatment, treatment "A" (g/m2): 4, 47 N + 7, 89 P205 + 19, 74 K20 and treatment "B"(g/m2): 8, 94 N + 15, 78 P205 + 19, 74 K20. Measurements were made to find out whether the treatments had produced any significant difference between the root strength of the two varieties (normal sweet Puma F I and super sweet Dessert R75 Fl) at the two dates of measurement (tasseling, milk stage) in the year 2003. The treatments with a high phosphorous ratio resulted in an apparent increase in root strength with both varieties. There was a detectable difference in root strength also between the two points of measurement, suggesting that root development had remained stable. The treatments produced significant increase not only in the root strength but also in the yields of both varieties.

Cancer continues to be one of the major health and socio-economic problems worldwide, despite considerable efforts to improve its early diagnosis and treatment. The identification of new constituents as biomarkers for early diagnosis of neoplastic cells and the discovery of new type of drugs with their mechanistic actions are crucial to improve cancer therapy. New drugs have entered the market, thanks to industrial and legislative efforts ensuring continuity of pharmaceutical development. New targets have been identified, but cancer therapy and the anti-cancer drug market still partly depend on anti-mitotic agents. The objective of this paper is to show the effects of KAR-2, a potent anti-mitotic compound, and TPPP/p25, a new unstructured protein, on the structural and functional characteristics of the microtubule system. Understanding the actions of these two potential effectors on the microtubule system could be the clue for early diagnosis and improvement of cancer therapy. [ABSTRACT FROM AUTHOR]

Tubulin polymerization-promoting protein2 (TPPP2) is one of the three paralogs of mammalian TPPP proteins. Its possible role in spermatogenesis is described in this narrative review. TPPP2 is expressed specifically in the male reproductive system, mainly in testes and sperm, and also in the epididymis. In testes, TPPP2 is exclusively expressed in elongating spermatids; in the epididymis, it is located in the middle piece of the sperm tail. TPPP2 is involved in spermiogenesis, in steps which are determinative for the formation and morphology of spermatids. The inhibition of TPPP2 decreases sperm motility (the curvilinear velocity of sperms), probably due to influencing mitochondrial energy production since TPPP2 knockout mice possess an impaired mitochondrial structure. There are data on the role of TPPP2 in various mammalian species: human, mouse, swine, and various ruminants; there is a significant homology among TPPP2s from different species. Experiments with Tppp2 -/- -mice show that the absence of TPPP2 results in decreased sperm count and serious dysfunction of sperm, including decreased motility; however, the in vitro capacitation and acrosome reaction are not influenced. The symptoms show that Tppp2 -/- -mice may be considered as a model for oligoasthenozoospermia.

The unicellular, parasitic fungi of the phylum Sanchytriomycota (sanchytrids) were discovered a few years ago. These unusual chytrid-like fungi parasitize algae. The zoospores of the species of the phylum contain an extremely long kinetosome composed of microtubular singlets or doublets and a non-motile pseudocilium (i.e., a reduced posterior flagellum). Fungi provide an ideal opportunity to test and confirm the correlation between the occurrence of flagellar proteins (the ciliome) and that of the eukaryotic cilium/flagellum since the flagellum occurs in the early-branching phyla and not in terrestrial fungi. Tubulin polymerization promoting protein (TPPP)-like proteins, which contain a p25alpha domain, were also suggested to belong to the ciliome and are present in flagellated fungi. Although sanchytrids have lost many of the flagellar proteins, here it is shown that they possess a DNA sequence possibly encoding long (animal-type) TPPP, but not the fungal-type one characteristic of chytrid fungi. Phylogenetic analysis of p25alpha domains placed sanchytrids into a sister position to Blastocladiomycota, similarly to species phylogeny, with maximal support.

Genome and transcriptome assembly data often contain DNA and RNA contaminations from external organisms, introduced during nucleotide extraction or sequencing. In this study, contamination of seed plant (Spermatophyta) transcriptomes/genomes with p25alpha domain encoding RNA/DNA was systematically investigated. This domain only occurs in organisms possessing a eukaryotic flagellum (cilium), which seed plants usually do not have. Nucleotide sequences available at the National Center for Biotechnology Information website, including transcriptome shotgun assemblies (TSAs), whole-genome shotgun contigs (WGSs), and expressed sequence tags (ESTs), were searched for sequences containing a p25alpha domain in Spermatophyta. Despite the lack of proteins containing the p25alpha domain, such fragments or complete mRNAs in some EST and TSA databases were found. A phylogenetic analysis showed that these were contaminations whose possible sources were microorganisms (flagellated fungi, protists) and arthropods/worms; however, there were cases where it cannot be excluded that the sequences found were genuine hits and not of external origin.

TPPP (tubulin polymerization promoting protein)-like proteins contain one or more p25alpha (Pfam05517) domains. TPPP-like proteins occur in different types as determined by their length (e.g., long-, short-, truncated-, and fungal-type TPPP) and include the protein apicortin, which possesses another domain, doublecortin (DCX, Pfam 03607). These various TPPP-like proteins are found in various phylogenomic groups. In particular, short-type TPPPs and apicortin are well-represented in the Myzozoa, which include apicomplexans and related taxa, chrompodellids, dinoflagellates, and perkinsids. The long-, truncated-, and fungal-type TPPPs are not found in the myzozoans. Apicortins are found in all apicomplexans except one piroplasmid species, present in several other myzozoans, and seem to be correlated with the conoid and apical complex. Short-type TPPPs are predominantly found in myzozoans that have flagella, suggesting a role in flagellum assembly or structure.

The seven most early diverging lineages of the 18 phyla of fungi are the non-terrestrial fungi, which reproduce through motile flagellated zoospores. There are genes/proteins that are present only in organisms with flagellum or cilium. It was suggested that TPPP-like proteins (proteins containing at least one complete or partial p25alpha domain) are among them, and a correlation between the incidence of the p25alpha domain and the eukaryotic flagellum was hypothesized. Of the seven phyla of flagellated fungi, six have been known to contain TPPP-like proteins. Aphelidiomycota, one of the early-branching phyla, has some species (e.g., Paraphelidium tribonematis ) that retain the flagellum, whereas the Amoeboaphelidium genus has lost the flagellum. The first two Aphelidiomycota genomes ( Amoeboaphelidium protococcorum and Amoeboaphelidium occidentale ) were sequenced and published last year. A BLASTP search revealed that A. occidentale does not have a TPPP, but A. protococcorum , which possesses pseudocilium, does have a TPPP. This TPPP is the 'long-type' which occurs mostly in animals as well as other Opisthokonta. P. tribonematis has a 'fungal-type' TPPP, which is found only in some flagellated fungi. These data on Aphelidiomycota TPPP proteins strengthen the correlation between the incidence of p25alpha domain-containing proteins and that of the eukaryotic flagellum/cilium.

Loss of the flagellum was an important step in the evolution of fungi. The flagellated fungi of the phylum Olpidiomycota are the closest relative of the non-flagellated terrestrial fungi. There are genes encoding proteins, the occurrence of which shows a strong correlation with the incidence of the flagellum. One of these gene/protein families is "TPPP-like proteins" whose main feature is the presence of the p25alpha domain. The functional link between TPPP and flagellum has also been shown. Most of the phyla of flagellated fungi have been known to contain TPPP-like proteins but Olpidiomycota was an exception. This study demonstrates that Olpidium bornovanus , similarly to some fungi of Chytridiomycota and Blastocladiomycota, has a "fungal-type" TPPP characterized by the presence of two (a complete and an incomplete) p25alpha domains.

Rediscoveries are not rare in biology. A recent example is the re-birth of the "fluctuation fit" concept developed by F. B. Straub and G. Szabolcsi in the sixties of the last century, under various names, the most popular of which is the "conformational selection". This theory offers an alternative to the "induced fit" concept by Koshland for the interpretation of the mechanism of protein-ligand interactions. A central question is whether the ligand induces a conformational change (as described by the induced fit model) or rather selects and stabilizes a complementary conformation from a pre-existing equilibrium of various states of the protein (according to the fluctuation fit/conformational selection model). Straub and Szabolcsi's role and the factors hindering the spread of the fluctuation fit theory are discussed in the context of the history of the Hungarian biology in the 1950s and 1960s., (© 2021. The Author(s).)

In 2009, apicortin was identified in silico as a characteristic protein of apicomplexans that also occurs in the placozoa, Trichoplax adhaerens . Since then, it has been found that apicortin also occurs in free-living cousins of apicomplexans (chromerids) and in flagellated fungi. It contains a partial p25-α domain and a doublecortin (DCX) domain, both of which have tubulin/microtubule binding properties. Apicortin has been studied experimentally in two very important apicomplexan pathogens, Toxoplasma gondii and Plasmodium falciparum . It is localized in the apical complex in both parasites. In T. gondii , apicortin plays a key role in shaping the structure of a special tubulin polymer, conoid. In both parasites, its absence or downregulation has been shown to impair pathogen-host interactions. Based on these facts, it has been suggested as a therapeutic target for treatment of malaria and toxoplasmosis.

TPPP proteins exhibiting microtubule stabilizing function constitute a eukaryotic protein superfamily, characterized by the presence of the p25alpha domain of various lengths. Vertebrate species possess three TPPP paralogs; all of them possess a full-length p25alpha domain of 160-170 amino acids and are encoded by three exons. Species of Endopterygota (Holometabola) have, besides a full-size TPPP ortholog, a protein with a truncated p25alpha domain as well, where the last coding exon, responsible for microtubule binding, is missing. It is not the result of an alternative splicing but is coded by another gene. In Drosophila melanogaster , they are named as CG45057 (long-type) and CG6709 (truncated). The truncated protein has been found in the Endopterygota orders Diptera, Coleoptera, Hymenoptera, Lepidoptera and Raphidioptera. In Lepidoptera, in several superfamilies (Gelechioidea, Bombycoidea, Noctuoidea, Pyraloidea) two paralogs of the truncated TPPP occur. Truncated orthologs (CG6709) were not found in other insects or in arthropods and are absent in any other organism, as well, while the long-type TPPPs (CG45057 orthologs) occur commonly in all animals. Thus it seems that CG6709 orthologs occur only in insects undergoing on metamorphosis., Competing Interests: The authors declare no conflict of interest., (© 2021 The Author(s).)

TPPP-like proteins, exhibiting microtubule stabilizing function, constitute a eukaryotic superfamily, characterized by the presence of the p25alpha domain. TPPPs in the strict sense are present in animals except Trichoplax adhaerens, which instead contains apicortin where a part of the p25alpha domain is combined with a DCX domain. Apicortin is absent in other animals and occurs mostly in the protozoan phylum, Apicomplexa. A strong correlation between the occurrence of p25alpha domain and that of the eukaryotic cilium/flagellum was suggested. Species of the deeper branching clades of Fungi possess flagellum but others lost it thus investigation of fungal genomes can help testing of this suggestion. Indeed, these proteins are present in early branching Fungi. Both TPPP and apicortin are present in Rozellomycota (Cryptomycota) and Chytridiomycota, TPPP in Blastocladiomycota, apicortin in Neocallimastigomycota, Monoblepharomycota and the non-flagellated Mucoromycota. Beside the "normal" TPPP occurring in animals, a special, fungal-type TPPP is also present in Fungi, in which a part of the p25alpha domain is duplicated. Dikarya, the most developed subkingdom of Fungi, lacks both flagellum and TPPPs. Thus it is strengthened that each ciliated/flagellated organism contains p25alpha domain-containing proteins while there are very few non-flagellated ones where p25alpha domain can be found., (Copyright © 2020 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

The sensing, integrating, and coordinating features of the eukaryotic cells are achieved by the complex ultrastructural arrays and multifarious functions of the cytoskeleton, including the microtubule network. Microtubules play crucial roles achieved by their decoration with proteins/enzymes as well as by posttranslational modifications. This review focuses on the Tubulin Polymerization Promoting Protein (TPPP/p25), a new microtubule associated protein, on its "regulatory functions by day and pathological functions at night". Physiologically, the moonlighting TPPP/p25 modulates the dynamics and stability of the microtubule network by bundling microtubules and enhancing the tubulin acetylation due to the inhibition of tubulin deacetylases. The optimal endogenous TPPP/p25 level is crucial for its physiological functions, to the differentiation of oligodendrocytes, which are the major constituents of the myelin sheath. Pathologically, TPPP/p25 forms toxic oligomers/aggregates with α-synuclein in neurons and oligodendrocytes in Parkinson's disease and Multiple System Atrophy, respectively; and their complex is a potential therapeutic drug target. TPPP/p25-derived microtubule hyperacetylation counteracts uncontrolled cell division. All these issues reveal the anti-mitotic and α-synuclein aggregation-promoting potency of TPPP/p25, consistent with the finding that Parkinson's disease patients have reduced risk for certain cancers., Competing Interests: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Apicortin is a characteristic protein of apicomplexan parasites which has recently been identified in their free-living cousins, chromerids as well. The placozoan Trichoplax adhaerens is the only animal possessing this protein and apicortin is one of its most abundant proteins. The recently published transcriptome of the cnidarian Porites astreoides contains an apicortin-like sequence. Other cnidarians do not have it, thus it is its first occurrence not only in this phylum but also in Eumetazoa. However, its translated amino acid sequence is more similar to apicomplexan apicortins than to that of T. adhaerens, the GC ratio is much higher than either the genome-wide GC ratio of P. astreoides or that of the placozoan apicortin gene, and phylogenetic analyses suggest that this apicortin has an apicomplexan origin. Although these data might be indicative for a horizontal gene transfer event, we should be cautious to state it; it is more probable that it is a contamination from a gregarine, a marine Apicomplexa. Thus T. adhaerens remains the only animal where the presence of apicortin is proved.

Tubulin polymerization promoting proteins (TPPPs) constitute a eukaryotic protein family. There are three TPPP paralogs in the human genome, denoted as TPPP1-TPPP3. TPPP1 and TPPP3 are intrinsically unstructured proteins (IUPs) that bind and polymerize tubulin and stabilize microtubules, but TPPP2 does not. Vertebrate TPPPs originated from the ancient invertebrate TPPP by two-round whole-genome duplication; thus, whether the tubulin/microtubule binding function of TPPP1 and TPPP3 is a newly acquired property or was present in the invertebrate orthologs (generally one TPPP per species) has been an open question. To answer this question, we investigated a TPPP from a simple and early branching animal, the sponge Suberites domuncula. Bioinformatics, biochemical, immunochemical, spectroscopic, and electron microscopic data showed that the properties of the sponge protein correspond to those of TPPP1; namely, it is an IUP that strongly binds tubulin and induces its polymerization, proving that these features of animal TPPPs have been evolutionarily conserved.

Apicomplexan parasites cause serious illnesses, including malaria, in humans and domestic animals. The presence of apicortins is predominantly characteristic of this phylum. All the apicomplexan species sequenced contain an apicortin which unites two conserved domains: DCX and partial p25alpha. This paper identifies novel apicortin orthologs in silico and corrects in several cases the erroneous sequences of hypothetical apicortin proteins of Cryptosporidium, Eimeria, and Theileria genera published in databases. Plasmodium apicortins, except from Plasmodium gallinaceum, differ significantly from the other apicomplexan apicortins. The feature of this ortholog suggests that only orthologs of Plasmodiums hosted by mammals altered significantly. The free-living Chromerida, Chromera velia, and Vitrella brassicaformis, contain three paralogs. Their apicomplexan-type and nonapicomplexan-type apicortins might be "outparalogs." The fungal ortholog, Rozella allomycis, found at protein level, and the algal Nitella mirabilis, found as Transcriptome Shotgun Assembly (TSA), are similar to the known Opisthokont (Trichoplax adhaerens, Spizellomyces punctatus) and Viridiplantae (Nicotiana tabacum) ones, since they do not contain the long, unstructured N-terminal part present in apicomplexan apicortins. A few eumetazoan animals possess apicortin-like (partial) sequences at TSA level, which may be either contaminations or the result of horizontal gene transfer; in some cases the contamination has been proved.

This paper highlights a general problem, namely that host genome sequences can easily be contaminated with parasite sequences, thus careful isolation of genetic material and careful bioinformatics analysis are needed in all cases. Two recently published genomes are shown here to be contaminated with sequences of apicomplexan parasites which belong to the Sarcocystidae family. Sequences of the characteristic apicomplexan organelle, the apicoplast, were used as queries in BLASTN searches against nucleotide sequences of various animal groups looking for possible contamination. Draft genomes of a bird, Colinus virginianus (Halley et al., 2014), and a bat, Myotis davidii (Zhang et al., 2013) were found to contain at least six and 17 contigs, respectively, originating from the apicoplast of an apicomplexan species, and other genes specific to this phylum can also be found in the published genomes. Obviously, the sources of the genetic material, the muscle and the kidney of the animals, respectively, contained the parasitic cysts. Phylogenetic analyses using 18S rRNA and internal transcribed spacer 1 genes show that the parasite contaminating C. virginianus is a species of Sarcocystis related to ones known to cycle between avian and mammalian hosts. In the case of M. davidii it belongs to the Nephroisospora genus, the only member of which, Nephroisospora eptesici, has been recently identified from the kidney of big brown bats (Eptesicus fuscus)., (Copyright © 2015 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.)

Recently, Aoki et al. [15] have been published a paper (Biochem. Biophys. Res. Commun. 445 (2014) 357-362.) in which they identified possible downstream genes required for the extension of peripheral axons in primary sensory neurons of zebrafish. Tppp was claimed as one of them but, as I show, it is the tppp3-like gene, a paralog of tppp, which plays this role. There are three tppp paralogs in fishes: tppp1 (named also tppp), tppp3 and tppp3-like. Tppp1 and tppp3 are the orthologs of the corresponding human genes, however, the classification of the third one is ambiguous. It is known that the genomes of the early vertebrate lineage underwent two complete genome duplications, which result in the presence of several paralogs in vertebrates. A teleost fish specific third whole genome duplication also occurred. Thus the tppp3-like gene can be either an ortholog of human TPPP2 or a fourth paralog (tppp4) absent in tetrapods but present in fishes; finally a tppp3a gene which can be originated from the third, fish specific, whole genome duplication. Comparing the sequences of vertebrate and recently available lamprey tppps I show that the tppp3-like gene is a TPPP2 ortholog. Synteny data are in accordance with this suggestion., (Copyright © 2015. Published by Elsevier Inc.)

The sensing, integrating, and coordinating features of the eukaryotic cells are achieved by the complex ultrastructural arrays and multifarious functions of the cytoskeletal network. Cytoskeleton comprises fibrous protein networks of microtubules, actin, and intermediate filaments. These filamentous polymer structures are highly dynamic and undergo constant and rapid reorganization during cellular processes. The microtubular system plays a crucial role in the brain, as it is involved in an enormous number of cellular events including cell differentiation and pathological inclusion formation. These multifarious functions of microtubules can be achieved by their decoration with proteins/enzymes that exert specific effects on the dynamics and organization of the cytoskeleton and mediate distinct functions due to their moonlighting features. This mini-review focuses on two aspects of the microtubule cytoskeleton. On the one hand, we describe the heteroassociation of tubulin/microtubules with metabolic enzymes, which in addition to their catalytic activities stabilize microtubule structures via their cross-linking functions. On the other hand, we focus on the recently identified moonlighting tubulin polymerization promoting protein, TPPP/p25. TPPP/p25 is a microtubule-associated protein and it displays distinct physiological or pathological (aberrant) functions; thus it is a prototype of Neomorphic Moonlighting Proteins. The expression of TPPP/p25 is finely controlled in the human brain; this protein is indispensable for the development of projections of oligodendrocytes that are responsible for the ensheathment of axons. The nonphysiological, higher or lower TPPP/p25 level leads to distinct CNS diseases. Mechanisms contributing to the control of microtubule stability and dynamics by metabolic enzymes and TPPP/p25 will be discussed., (Copyright © 2013 Wiley Periodicals, Inc.)

A eukaryotic protein family, the tubulin polymerization promoting proteins (TPPPs), has recently been identified. It has been termed after its first member, TPPP/p25 or TPPP1, which exhibits microtubule-stabilizing function and plays a role in neurodegenerative diseases. In mammalian genomes, two further paralogues, TPPP2 and TPPP3, can be found. In this article, I show that TPPP1 and TPPP3, but not TPPP2, are included in paralogons, on human chromosomes, Hsa5 and Hsa16, respectively. I suggest that the single non-vertebrate tppp gene was duplicated in the first round of whole-genome duplication in the vertebrate lineage giving rise to tppp1 and the precursor of tppp2/tppp3. The existence of a teleost fish-specific fourth paralogue, tppp4, has also been raised, but it is not supported by synteny analysis. Alternatively, the new group can be considered as the fish orthologue of TPPP2. The case that the new group is the consequence of the teleost fish-specific whole-genome duplication (3R) cannot be excluded.

Background: The disordered Tubulin Polymerization Promoting Protein/p25 (TPPP/p25) modulates the dynamics and stability of the microtubule system. In this paper the role of dimerization in its microtubule-related functions is established, and an approach is proposed to evaluate thermodynamic constants for multiple equilibrium systems from ITC measurements., Methods: For structural studies size exclusion chromatography, SDS-PAGE, chemical cross-linking, circular dichroism, fluorescence spectroscopy and isothermal titration calorimetry were used; the functional effect was analyzed by tubulin polymerization assay. Numerical simulation of the multiple equilibrium was performed with Mathematica software., Results: The dimerization of TPPP/p25 is promoted by elevation of the protein concentration and by GTP addition. The dimeric form displaying enhanced tubulin polymerization promoting activity is stabilized by disulfide bond or chemical cross-linking. The GTP binding to the dimeric form (Kd-GTP=200 μM) is tighter with one order of magnitude than to the monomeric one leading to the enrichment of the dimers. A mathematical model elaborated for the multiple equilibrium of the TPPP/p25-GTP system was validated by fitting the GTP-dependent changes of ellipticity and fluorescence signal in the course of TPPP/p25 titrations. The evaluation of the equilibrium constants rendered it possible to determine the thermodynamic parameters of the association of different TPPP/p25 forms with GTP from ITC measurements., Conclusions/general Significance: The dimerization of TPPP/p25 with favorable physiological functional potency is proposed to play significant role in the fine tuning of TPPP/p25-mediated microtubule assembly; the unfolded monomers might be involved in the formation of pathological inclusions characteristic for Parkinson's disease and other synucleinopathies., (Copyright © 2012 Elsevier B.V. All rights reserved.)

The introduction of the term 'Tubulin Polymerization Promoting Protein (TPPP)-like proteins' is suggested. They constitute a eukaryotic protein superfamily, characterized by the presence of the p25alpha domain (Pfam05517, IPR008907), and named after the first identified member, TPPP/p25, exhibiting microtubule stabilizing function. TPPP-like proteins can be grouped on the basis of two characteristics: the length of their p25alpha domain, which can be long, short, truncated or partial, and the presence or absence of additional domain(s). TPPPs, in the strict sense, contain no other domains but one long or short p25alpha one (long- and short-type TPPPs, respectively). Proteins possessing truncated p25alpha domain are first described in this paper. They evolved from the long-type TPPPs and can be considered as arthropod-specific paralogs of long-type TPPPs. Phylogenetic analysis shows that the two groups (long-type and truncated TPPPs) split in the common ancestor of arthropods. Incomplete p25alpha domains can be found in multidomain TPPP-like proteins as well. The various subfamilies occur with a characteristic phyletic distribution: e. g., animal genomes/proteomes contain almost without exception long-type TPPPs; the multidomain apicortins occur almost exclusively in apicomplexan parasites. There are no data about the physiological function of these proteins except two human long-type TPPP paralogs which are involved in developmental processes of the brain and the musculoskeletal system, respectively. I predict that the superfamily members containing long or partial p25alpha domain are often intrinsically disordered proteins, while those with short or truncated domain(s) are structurally ordered. Interestingly, members of this superfamily connected or maybe connected to diseases are intrinsically disordered proteins.

The disordered tubulin polymerization promoting protein (TPPP/p25) was found to be co-enriched in neuronal and glial inclusions with α-synuclein in Parkinson disease and multiple system atrophy, respectively; however, co-occurrence of α-synuclein with β-amyloid (Aβ) in human brain inclusions has been recently reported, suggesting the existence of mixed type pathologies that could result in obstacles in the correct diagnosis and treatment. Here we identified TPPP/p25 as an interacting partner of the soluble Aβ oligomers as major risk factors for Alzheimer disease using ProtoArray human protein microarray. The interactions of oligomeric Aβ with proteins involved in the etiology of neurological disorders were characterized by ELISA, surface plasmon resonance, pelleting experiments, and tubulin polymerization assay. We showed that the Aβ(42) tightly bound to TPPP/p25 (K(d) = 85 nm) and caused aberrant protein aggregation by inhibiting the physiologically relevant TPPP/p25-derived microtubule assembly. The pair-wise interactions of Aβ(42), α-synuclein, and tubulin were found to be relatively weak; however, these three components formed soluble ternary complex exclusively in the absence of TPPP/p25. The aggregation-facilitating activity of TPPP/p25 and its interaction with Aβ was monitored by electron microscopy with purified proteins by pelleting experiments with cell-free extracts as well as by confocal microscopy with CHO cells expressing TPPP/p25 or amyloid. The finding that the interaction of TPPP/p25 with Aβ can produce pathological-like aggregates is tightly coupled with unusual pathology of the Alzheimer disease revealed previously; that is, partial co-localization of Aβ and TPPP/p25 in the case of diffuse Lewy body disease with Alzheimer disease.

A new protein, termed apicortin, has recently been identified, which occurs only in the placozoan animal Trichoplax adhaerens and in the genomes of all currently sequenced apicomplexan parasites (e.g., Toxoplasma, Plasmodium, etc.). Apicortins unite two conserved domains, a DCX motif and a partial p25alpha sequence, which are singly found in diverse other proteins, in doublecortins and TPPPs, respectively. Here I show that although apicortin has a limited phylogenomic distribution, its occurrence is broader than thought previously. It has been identified in another primitive opisthokont, in the chytrid fungus, Spizellomyces punctatus. Apicortins can be divided into two subgroups: apicomplexan and non-apicomplexan ones. The main difference is that the former ones possess a long, N-terminal extension predicted to be disordered, which is missing in the other subgroup. The appearance of the extension in apicomplexan apicortins is an "innovation" of this phylum, and may play a functional role in the protein-protein interactions., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Motivation: Predictions, and experiments to a lesser extent, following the decoding of the human genome showed that a significant fraction of gene products do not have well-defined 3D structures. While the presence of structured domains traditionally suggested function, it was not clear what the absence of structure implied. These and many other findings initiated the extensive theoretical and experimental research into these types of proteins, commonly known as intrinsically disordered proteins (IDPs). Crucial to understanding IDPs is the evaluation of structural predictors based on different principles and trained on various datasets, which is currently the subject of active research. The view is emerging that structural disorder can be considered as a separate structural category and not simply as absence of secondary and/or tertiary structure. IDPs perform essential functions and their improper functioning is responsible for human diseases such as neurodegenerative disorders.

The disordered Tubulin Polymerization Promoting Protein/p25 (TPPP/p25) modulates the dynamics and stability of the microtubule system and plays a crucial role in differentiation of oligodendrocytes. Here we first demonstrated by multinuclear NMR that the extended disordered segments are localized at the N- and C-terminals straddling a flexible region. We showed by affinity chromatography, fluorescence spectroscopy and circular dichroism that GTP binds to TPPP/p25 likely within the flexible region; neither positions nor intensities of the peaks in the assigned terminals were affected by GTP. In addition, we demonstrated that TPPP/p25 specifically hydrolyses GTP in an Mg(2+)-dependent manner. The GTPase activity is comparable with the intrinsic activities of small G proteins suggesting its potential role in multiple physiological processes., (Copyright © 2011 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.)