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Mycoplasma genitalium (M. genitalium) has evolved as a superbug, and the developing antimicrobial resistance with just a few treatment options available is an imminent concern. Due to the emergence of antibiotic resistance, a new antibiotic class or medications are required to combat this pathogen. The phosphate acetyltransferase (PTA) enzyme can be a suitable drug target which is essential for M. genitalium survival and involves in acetate metabolism. To efficiently find potent inhibitors, structure-based drug design approaches targeting the PTA of M. genitalium have been established. In this study, the three most potent phytochemical inhibitors were predicted from virtual screening and these are sitostanyl ferulate, beta-sitosterol-beta-d-glucoside, and brassinolide, with binding energies of − 9.66, − 9.60, and − 9.48 kcal/mol, respectively. The active site residues Thr-125, Arg-300, Ser-299, Tyr-272, and Lys-273 appear to be critical in binding the three predicted potent inhibitors. The results of the molecular dynamics study indicate that the three predicted phytochemical inhibitors have formed stable bonds with PTA. Molecular Mechanics Poisson–Boltzmann Surface Area (MM-PBSA) was utilized for the estimation of binding free energy of PTA-phytochemical complexes. Taken together, the findings of our computational work might aid in the development of possible potential drugs to treat and ameliorate the severity of M. genitalium infection. [ABSTRACT FROM AUTHOR]

Key message: Map-based cloning of maize ms33 gene showed that ZmMs33 encodes a sn-2 glycerol-3-phosphate acyltransferase, the ortholog of rice OsGPAT3, and it is essential for male fertility in maize.Abstract: Genetic male sterility has been widely studied for its biological significance and commercial value in hybrid seed production. Although many male-sterile mutants have been identified in maize (Zea mays L.), it is likely that most genes that cause male sterility are unknown. Here, we report a recessive genetic male-sterile mutant, male sterility33 (ms33), which displays small, pale yellow anthers, and complete male sterility. Using a map-based cloning approach, maize GRMZM2G070304 was identified as the ms33 gene (ZmMs33). ZmMs33 encodes a novel sn-2 glycerol-3-phosphate acyltransferase (GPAT) in maize. A functional complementation experiment showed that GRMZM2G070304 can rescue the male-sterile phenotype of the ms33-6029 mutant. GRMZM2G070304 was further confirmed to be the ms33 gene via targeted knockouts induced by the clustered regularly interspersed short palindromic repeats (CRISPR)/Cas9 system. ZmMs33 is preferentially expressed in the immature anther from the quartet to early-vacuolate microspore stages and in root tissues at the fifth leaf growth stage. Phylogenetic analysis indicated that ZmMs33 and OsGPAT3 are evolutionarily conserved for anther and pollen development in monocot species. This study reveals that the monocot-specific GPAT3 protein plays an important role in male fertility in maize, and ZmMs33 and mutants in this gene may have value in maize male-sterile line breeding and hybrid seed production. [ABSTRACT FROM AUTHOR]

Key message: Two round-leaf mutants, rl-1 and rl-2, were identified from EMS-induced mutagenesis. High throughput sequencing and map-based cloning suggested CsPID encoding a Ser/Thr protein kinase as the most possible candidate for rl-1. Rl-2 was allelic to Rl-1.Abstract: Leaf shape is an important plant architecture trait that is affected by plant hormones, especially auxin. In Arabidopsis, PINOID (PID), a regulator for the auxin polar transporter PIN (PIN-FORMED) affects leaf shape formation, but this function of PID in crop plants has not been well studied. From an EMS mutagenesis population, we identified two round-leaf (rl) mutants, C356 and C949. Segregation analysis suggested that both mutations were controlled by single recessive genes, rl-1 and rl-2, respectively. With map-based cloning, we show that CsPID as the candidate gene of rl-1; a non-synonymous SNP in the second exon of CsPID resulted in an amino acid substitution and the round leaf phenotype. As compared in the wild type plant, CsPID had significantly lower expression in the root, leaf and female flowers in C356, which may result in the less developed roots, round leaves and abnormal female flowers, respectively in the rl-1 mutant. Among the three copies of PID genes, CsPID, CsPID2 and CSPID2L (CsPID2-like) in the cucumber genome, CsPID was the only one with significantly differential expression in adult leaves between WT and C356 suggesting CsPID plays a main role in leaf shape formation. The rl-2 mutation in C949 was also cloned, which was due to another SNP in a nearby location of rl-1 in the same CsPID gene. The two round leaf mutants and the work presented herein provide a good foundation for understanding the molecular mechanisms of CsPID in cucumber leaf development. [ABSTRACT FROM AUTHOR]

The ST0452 protein from the thermophilic archaean Sulfolobus tokodaii has been identified as an enzyme with multiple sugar-1-phosphate nucleotidylyltransferase and amino-sugar-1-phosphate acetyltransferase (amino-sugar-1-P AcTase) activities. Analysis of the protein showed that in addition to glucosamine-1-phosphate (GlcN-1-P) AcTase activity, it possesses unique galactosamine-1-phosphate (GalN-1-P) AcTase activity not detected in any other proteins. Comparison of the crystal structures of the ST0452 protein and GlmU from Escherichia coli (EcGlmU), which possesses only GlcN-1-P AcTase activity, showed that the overall sequence identity between these two proteins is less than 25 %, but the amino acid residues predicted to comprise the catalytic center of EcGlmU are conserved in the ST0452 protein. To understand the molecular mechanism by which the ST0452 amino-sugar-1-P AcTase activity recognizes two independent substrates, several ST0452 substitution and truncation mutant proteins were constructed and analyzed. We found that His308 is essential for both GalN-1-P and GlcN-1-P AcTase activities, whereas Tyr311 and Asn331 are important only for the GalN-1-P AcTase activity. In addition, deletion of the C-terminal 5 or 11 residues showed that the 11-residue C-terminal region exerts a modest stimulatory effect on GalN-1-P AcTase activity but dramatically suppresses GlcN-1-P AcTase activity. This region also appears to make an important contribution to the thermostability of the entire ST0452 protein. Systematic deletions from the C-terminus also demonstrated that the C-terminal region with the β-helix structure has an important role mediating the trimerization of the ST0452 protein. This is the first report of an analysis of a thermostable archaeal enzyme exhibiting multiple amino-sugar-1-P AcTase activities. [ABSTRACT FROM AUTHOR]

Interest in sustainable development has led to efforts to replace petrochemical-based monomers with biomass-based ones. Itaconic acid, a C5-dicarboxylic acid, is a potential monomer for the chemical industry with many prospective applications. cis-aconitate decarboxylase (CadA) is the key enzyme of itaconate production, converting the citric acid cycle intermediate cis-aconitate into itaconate. Heterologous expression of cadA from Aspergillus terreus in Escherichia coli resulted in low CadA activities and production of trace amounts of itaconate on Luria-Bertani (LB) medium (<10 mg/L). CadA was primarily present as inclusion bodies, explaining the low activity. The activity was significantly improved by using lower cultivation temperatures and mineral medium, and this resulted in enhanced itaconate titres (240 mg/L). The itaconate titre was further increased by introducing citrate synthase and aconitase from Corynebacterium glutamicum and by deleting the genes encoding phosphate acetyltransferase and lactate dehydrogenase. These deletions in E. coli's central metabolism resulted in the accumulation of pyruvate, which is a precursor for itaconate biosynthesis. As a result, itaconate production in aerobic bioreactor cultures was increased up to 690 mg/L. The maximum yield obtained was 0.09 mol itaconate/mol glucose. Strategies for a further improvement of itaconate production are discussed. [ABSTRACT FROM AUTHOR]

Elimination of acetate overflow in aerobic cultivation of Escherichia coli would improve many bioprocesses as acetate accumulation in the growth environment leads to numerous negative effects, e.g. loss of carbon, inhibition of growth, target product synthesis, etc. Despite many years of studies, the mechanism and regulation of acetate overflow are still not completely understood. Therefore, we studied the growth of E. coli K-12 BW25113 and several of its mutant strains affecting acetate-related pathways using the continuous culture method accelerostat (A-stat) at various specific glucose consumption rates with the aim of diminishing acetate overflow. Absolute quantitative exo-metabolome and proteome analyses coupled to metabolic flux analysis enabled us to demonstrate that onset of acetate overflow can be postponed and acetate excretion strongly reduced in E. coli by coordinated activation of phosphotransacetylase-acetyl-CoA synthetase (PTA-ACS) and tricarboxylic acid (TCA) cycles. Fourfold reduction of acetate excretion (2 vs. 8 % from total carbon) at fastest growth compared to wild type was achieved by deleting the genes responsible for inactivation of acetyl-CoA synthetase protein ( pka) and TCA cycle regulator arcA. The Δ pka Δ arcA strain did not accumulate any other detrimental by-product besides acetate and showed identical μ and only ~5 % lower biomass yield compared to wild type. We conclude that a fine-tuned coordination between increasing the recycling capabilities of acetate in the PTA-ACS node through a higher concentration of active acetate scavenging Acs protein and downstream metabolism throughput in the TCA cycle is necessary for diminishing overflow metabolism of acetate in E. coli and achieving higher target product production in bioprocesses. [ABSTRACT FROM AUTHOR]

Cyclophilins belong to the peptidyl-prolyl cis/trans isomerase family of enzymes (EC 5.2.1.8), which accelerate protein folding by catalysing the cis/trans isomerisation of proline imidic peptide bonds. In the present study, by a combination of bioinformatics methods, we identify phosphate acetyltransferase isoforms, AvPTA-1 and AvPTA-2, as potential interacting partners of AvPPIB, the cytoplasmic cyclophilin from Azotobacter vinelandii, and demonstrate their physical interaction by co-expression studies. A decrease in AvPPIB PPIase activity, in the presence of AvPTA-1 or AvPTA-2, further confirms each interaction. Phosphate acetyltransferases (EC 2.3.1.8) catalyse the reversible transfer of the acetyl group from acetyl-P to CoA, forming acetyl-CoA and inorganic phosphate. We examined the effect of AvPPIB on the enzymatic activity of both phosphate acetyltransferase isoforms, and noticed an enhancement of the activity, as well as an alteration of the K of each isoform, for the reaction substrates, indicating a possible function of AvPPIB in phosphate acetyltransferase activity modulation. Although PPIase activity seems not to be essential for these interactions, since AvPPIB active site mutant still interacts with both isoforms, it is responsible for the observed phosphate acetyltransferase activity enhancement as AvPPIB enhanced to a significantly lower extent the phosphate acetyltransferase activity of both isoforms compared with AvPPIB. [ABSTRACT FROM AUTHOR]

etate is abundant in soil contributing to a great extent on carbon cycling in nature. Phosphate acetyltransferase (Pta, EC 2.3.1.8) catalyzes the reversible transfer of the acetyl group from acetyl-P to CoA forming acetyl-CoA and inorganic phosphate, participating to acetate assimilation/dissimilation reactions. In the present study, we demonstrate that Azotobacter vinelandii, a nitrogen-fixing, free-living, soil bacterium, possesses two class II phosphate acetyltransferase isoforms, AvPTA-1 and AvPTA-2, with different kinetic properties. At the acetyl-CoA forming direction, AvPTA-1 has lower affinity for acetyl-P and higher affinity for CoA than AvPTA-2 while at the acetyl-P forming direction; activity was measured only for AvPTA-1. Quantification of their expression patterns by RT-qPCR indicated that both genes are expressed during exponential growth on glucose or acetate and are down-regulated in the stationary phase. The ammonium availability during acetate growth resulted in up-regulation of Avpta- 2 expression only. Further, the gene expression patterns of other related gene transcripts were also investigated, in order to understand the influence of each pathway in the assimilation/dissimilation of acetate. [ABSTRACT FROM AUTHOR]

The halophilic archaea Halococcus (Hc.) saccharolyticus, Haloferax (Hf.) volcanii, and Halorubrum (Hr.) saccharovorum were found to generate acetate during growth on glucose and to utilize acetate as a growth substrate. The mechanisms of acetate formation from acetyl-CoA and of acetate activation to acetyl-CoA were studied. Hc. saccharolyticus, exponentially growing on complex medium with glucose, formed acetate and contained ADP-forming acetyl-CoA synthetase (ADP-ACS) rather than acetate kinase and phosphate acetyltransferase or AMP-forming acetyl-CoA synthetase. In the stationary phase, the excreted acetate was completely consumed, and cells contained AMP-forming acetyl-CoA synthetase (AMP-ACS) and a significantly reduced ADP-ACS activity. Hc. saccharolyticus, grown on acetate as carbon and energy source, contained only AMP-ACS rather than ADP-ACS or acetate kinase. Cell suspensions of Hc. saccharolyticus metabolized acetate only when they contained AMP-ACS activity, i.e., when they were obtained after growth on acetate or from the stationary phase after growth on glucose. Suspensions of exponential glucose-grown cells, containing only ADP-ACS but not AMP-ACS, did not consume acetate. Similar results were obtained for the phylogenetic distantly related halophilic archaea Hf. volcanii and Hf. saccharovorum. We conclude that, in halophilic archaea, the formation of acetate from acetyl-CoA is catalyzed by ADP-ACS, whereas the activation of acetate to acetyl-CoA is mediated by an inducible AMP-ACS. [ABSTRACT FROM AUTHOR]

The anaerobic hyperthermophilic archaea Desulfurococcus amylolyticus, Hyperthermus butylicus, Thermococcus celer, Pyrococcus woesei, the hyperthermophilic bacteria Thermotoga maritima and Clostridium thermohydrosulfuricum and the aerobic mesophilic archaeon Halobacterium saccharovorum were grown either on complex media, on sugars or on pyruvate as carbon and energy sources. During growth acetate was formed as fermentation product by all organisms. The enzymes involved in acetyl-CoA formation from pyruvate and in acetate formation from acetyl-CoA were investigated: These data indicate that acetyl-CoA synthetase (ADP forming) represents a typical archaeal property rather than an enzyme specific for hyperthermophiles. It is proposed that in all acetate forming archaea the formation of acetate and of ATP from acetyl-CoA, ADP and P are catalyzed by acetyl-CoA synthetase (ADP forming), whereas in all acetate forming (eu)bacteria these reactions are catalyzed by two enzymes, phosphate acetyltransferase and acetate kinase. [ABSTRACT FROM AUTHOR]