Search

Intolerance of uncertainty (IU) has been suggested to be associated with emotional perceptions and evaluations. Several studies have also revealed that IU is related to cognitive preferences, in particular gain-relevant risk preference. Nevertheless, it is still unclear whether both prospective and inhibitory IU, two dimensions of IU, predict gain-related and moreover, loss-relevant risky preference. More importantly, it is unknown whether the associations between IU and risk preference are modulated by biological factors (e.g., genes). Therefore, the current study investigated whether prospective and inhibitory IU were associated with gain-/loss-related risk preference and whether the associations were modulated by an impulsivity control-related gene, tryptophan hydroxylase 1 (TPH1) gene (A779C, rs1799913) through recruiting 222 healthy Chinese participants. Results showed that prospective IU was correlated with gain-relevant risk averse. There was not a significant association between IU and loss-relevant risk preference. Nevertheless, further analysis revealed that the association was modulated by the TPH1 genotype. Prospective and inhibitory IU predicted loss-relevant risk averse specifically for TPH1 AC genotype carriers but not for other genotype carriers (i.e., AA or CC). The findings emphasize the associations between IU and risk preference depending on frame and genetic variance., Author(s): Huiyan Lin [sup.1] [sup.2] , Junkai Yang [sup.1] , Jianping Hu [sup.1] Author Affiliations: (1) https://ror.org/04grzdh47, grid.464294.9, 0000 0004 1805 7312, Laboratory for Behavioral and Regional Finance, Guangdong University [...]

Author(s): Ole Herud-Sikimic [sup.1] , Andre C. Stiel [sup.1] [sup.2] , Martina Kolb [sup.1] , Sooruban Shanmugaratnam [sup.1] [sup.3] , Kenneth W. Berendzen [sup.4] , Christian Feldhaus [sup.1] , Birte [...], One of the most important regulatory small molecules in plants is indole-3-acetic acid, also known as auxin. Its dynamic redistribution has an essential role in almost every aspect of plant life, ranging from cell shape and division to organogenesis and responses to light and gravity.sup.1,2. So far, it has not been possible to directly determine the spatial and temporal distribution of auxin at a cellular resolution. Instead it is inferred from the visualization of irreversible processes that involve the endogenous auxin-response machinery.sup.3-7; however, such a system cannot detect transient changes. Here we report a genetically encoded biosensor for the quantitative in vivo visualization of auxin distribution. The sensor is based on the Escherichia coli tryptophan repressor.sup.8, the binding pocket of which is engineered to be specific to auxin. Coupling of the auxin-binding moiety with selected fluorescent proteins enables the use of a fluorescence resonance energy transfer signal as a readout. Unlike previous systems, this sensor enables direct monitoring of the rapid uptake and clearance of auxin by individual cells and within cell compartments in planta. By responding to the graded spatial distribution along the root axis and its perturbation by transport inhibitors--as well as the rapid and reversible redistribution of endogenous auxin in response to changes in gravity vectors--our sensor enables real-time monitoring of auxin concentrations at a (sub)cellular resolution and their spatial and temporal changes during the lifespan of a plant. A genetically encoded sensor for the quantitative visualization of auxin distribution in plants enables real-time monitoring of its uptake and clearance by individual cells and within cellular compartments.

Chlamydia trachomatis is spread by close social contact or sexual activity. Worldwide, C. trachomatis is the leading preventable cause of blindness and bacterial sexually transmitted infections (STIs). Various typing techniques [...]

Buchnera aphidicola BCc has lost its symbiotic role as the tryptophan supplier to the aphid Cinara cedri. We report the presence of a plasmid in this endosymbiont that contains the trpEG genes. The remaining genes for the pathway (trpDCBA) are located on the chromosome of the secondary endosymbiont 'Candidatus Serratia symbiotica.' Thus, we propose that a symbiotic consortium is necessary to provide tryptophan.

Voltage-dependent calcium channels consist of a pore-forming subunit ([Ca.sub.v][[alpha].sub.1]) that includes all the molecular determinants of a voltage-gated channel, and several accessory subunits. The ancillary [beta]-subunit ([Ca.sub.v][beta]) is a potent activator of voltage-dependent calcium channels, but the mechanisms and structural bases of this regulation remain elusive. [Ca.sub.v][beta] binds reversibly to a conserved consensus sequence in [Ca.sub.v][[alpha].sub.1], the [[alpha].sub.1]-interaction domain (AID), which forms an [alpha]-helix when complexed with [Ca.sub.v][beta]. Conserved aromatic residues face to one side of the helix and strongly interact with a hydrophobic pocket on [Ca.sub.v][beta]. Here, we studied the effect of mutating residues located opposite to the AID-[Ca.sub.v[[beta] contact surface in [Ca.sub.v]l.2. Substitution of AID-exposed residues by the corresponding amino acids present in other [Ca.sub.v][[alpha].sub.1] subunits (E462R, K465N, D469S, and Q473K) hinders [Ca.sub.v][beta]'s ability to increase ionic-current to charge-movement ratio (I/Q) without changing the apparent affinity for [Ca.sub.v][beta]. At the single channel level, these [Ca.sub.v]l.2 mutants coexpressed with [Ca.sub.v][beta].sub.2a], visit high open probability mode less frequently than wildtype channels. On the other hand, [Ca.sub.v]l.2 carrying either a mutation in the conserved tryptophan residue (W470S, which impairs [Ca.sub.v][beta] binding), or a deletion of the whole AID sequence, does not exhibit [Ca.sub.v][beta]- induced increase in I/Q. In addition, we observed a shift in the voltage dependence of activation by +12 mV in the AID-deleted channel in the absence of [Ca.sub.v][beta], suggesting a direct participation of these residues in the modulation of channel activation. Our results show that [Ca.sub.v][beta]-dependent potentiation arises primarily from changes in the modal gating behavior. We envision that [Ca.sub.v][beta] spatially reorients AID residues that influence the channel gate. These findings provide a new framework for understanding modulation of VDCC gating by [Ca.sub.v][beta].

The Pseudomonas aeruginosa type III secretion system (T3SS) is known to be a very important virulence factor in acute human infections, but it is less important in maintaining chronic infections in which T3SS genes are downregulated. In vitro, the activation of T3SS expression involves a positive activating loop that acts on the transcriptional regulator ExsA. We have observed that in vivo T3SS expression is cell density-dependent in a manner that does not need known quorumsensing (QS) signals. In addition, stationary-phase culture supernatants added to exponentialphase growing strains can inhibit T3SS expression. The analysis of transposon insertion mutants showed that the production of such T3SS-inhibiting signals might depend on tryptophan synthase and hence tryptophan, which is the precursor of signalling molecules such as indole-3-acetic acid (IAA), kynurenine and Pseudomonas quinolone signal (PQS). Commercially available tryptophan-derived molecules were tested for their role in the regulation of T3SS expression. At millimolar concentrations, IAA, 1-naphthalacetic acid (NAA) and 3-hydroxykynurenine inhibited T3SS expression. Inactivation of the tryptophan dioxygenase-encoding kynA gene resulted in a decrease in the T3SS-inhibiting activity of supernatants. These observations suggest that tryptophan catabolites are involved in the downregulation of T3SS expression in the transition from a low- to a high-cell-density state.

The Bacillus subtilis anti-TRAP protein regulates the ability of the tryptophan-activated TRAP protein to bind to trp operon leader RNA and promote transcription termination. AT synthesis is regulated both transcriptionally and translationally by uncharged tRN[A.sup.Trp]. In this study, we examined the roles of AT synthesis and tRN[A.sup.Trp] charging in mediating physiological responses to tryptophan starvation. Adding excess phenylalanine to wild-type cultures reduced the charged tRN[A.sup.Trp] level from 80% to 40%; the charged level decreased further, to 25%, in an AT-deficient mutant. Adding tryptophan with phenylalanine increased the charged tRN[A.sup.Trp] level, implying that phenylalanine, when added alone, reduces the availability of tryptophan for tRN[A.sup.Trp] charging. Changes in the charged tRN[A.sup.Trp] level observed during growth with added phenylalanine were associated with increased transcription of the genes of tryptophan metabolism. Nutritional shift experiments, from a medium containing tryptophan to a medium with phenylalanine and tyrosine, showed that wild-type cultures gradually reduced their charged tRN[A.sup.Trp] level. When this shift was performed with an AT-deficient mutant, the charged tRN[A.sup.Trp] level decreased even further. Growth rates for wild-type and mutant strains deficient in AT or TRAP or that overproduce AT were compared in various media. A lack of TRAP or overproduction of AT resulted in phenylalanine being required for growth. These findings reveal the importance of AT in maintaining a balance between the synthesis of tryptophan versus the synthesis of phenylalanine, with the level of charged tRN[A.sup.Trp] acting as the crucial signal regulating AT production.

Phosphoribosyl amine (PRA) is an intermediate in purine biosynthesis and also required for thiamine biosynthesis in Salmonella enterica. PRA is normally synthesized by phosphoribosyl pyrophosphate amidotransferase, a high-turnover enzyme of the purine biosynthetic pathway encoded by purF. However, PurFindependent PRA synthesis has been observed in strains having different genetic backgrounds and growing under diverse conditions. Genetic analysis has shown that the anthranilate synthase-phosphoribosyltransferase (AS-PRT) enzyme complex, involved in the synthesis of tryptophan, can playa role in the synthesis of PRA. This work describes the in vitro synthesis of PRA in the presence of the purified components of the AS-PRT complex. Results from in vitro assays and in vivo studies indicate that the cellular accumulation of phosphoribosyl anthranilate can result in nonenzymatic PRA formation sufficient for thiamine synthesis. These studies have uncovered a mechanism used by cells to redistribute metabolites to ensure thiamine synthesis and may define a general paradigm of metabolic robustness.

Conserved trp genes encode enzymes that catalyze tryptophan biosynthesis in all three biological domains, and studies of their expression in Bacteria and eukaryotes have revealed a variety of different regulatory mechanisms. The results reported here provide the first detailed description of an archaeal trp gene regulatory system. We have established that the trpEGCFBAD operon in Methanothermobacter thermautotrophicus is transcribed divergently from a gene (designated trpY) that encodes a tryptophan-sensitive transcription regulator. TrpY binds to TRP box sequences (consensus, TGTACA) located in the overlapping promoter regions between trpY and trpE, inhibiting trpY transcription in the absence of tryptophan and both trpY and trpEGCFBAD transcription in the presence of tryptophan. TrpY apparently inhibits trpY transcription by blocking RNA polymerase access to the site of trpY transcription initiation and represses trpEGCFBAD transcription by preventing TATA box binding protein (TBP) binding to the TATA box sequence. Given that residue 2 (W2) is the only tryptophan in TrpY and in TrpY homologues in other Euryarchaea and that there is only one tryptophan codon in the entire trpEGCFBAD operon (trpB encodes W175), expression of the trp operon may also be regulated in vivo by the supply of charged tRN[A.sup.Trp] available to translate the second codon of the trpY mRNA.

Research has been conducted on plant hormone auxin which regulates plant development and growth. The authors provide the evidence that Arabidopsis cytochrome P450s CYP79B2 and CYP79B3, converting tryptophan to indole-3-acetaldoxin, are the important enzymes in auxin biosynthesis in vivo.

Research has been conducted on the antimicrobial peptides which belong to the pediocin-like bacteriocin family. The role of the tryptophan residue mutations in the pediocin-like bacteriocin sakasin P has been investigated and the results are presented.

Research has been conducted on Escherichia coli tryptophan indole-lyase. The preparation of the mutant forms of the indole-lyase carried out in determining the role of these residues in the catalytic mechanism and in reaction specificity for L-tryptophan is reported.

Research has been conducted on the receptor-binding activity of intimin residues involved in the intimate bacterial adhesion to intestinal epithelium. The effect of the tryptophan residues' site-directed mutagenesis on the intemin-translocated intemin receptor interactions has been investigated and the results indicate that the substitutions have modulated intimin activity.

In plants, the tryptophan biosynthetic pathway provides a number of important secondary metabolites including the growth regulator indole-3-acetic acid (IAA) and indole glucosinolate defense compounds. Genes encoding tryptophan pathway enzymes are transcriptionally induced by a variety of stress signals, presumably to increase the production of both tryptophan and secondary metabolites during defense responses. To understand the mechanism of transcriptional induction, we isolated altered tryptophan regulation (atr) mutants in Arabidopsis thaliana with activated transcription of tryptophan genes. One atr complementation group consisted of mutations in the cytochrome P450 gene CYP83B1. Mutant plants had constitutively activated expression of the ATR1 Myb factor gene, which was identified as a positive regulator of tryptophan genes via the atr mutant screen, cyp83B1 mutants were previously characterized as having defects in IAA homeostasis due to perturbation of secondary tryptophan metabolism. Our findings indicate that the upregulation of tryptophan pathway genes might also contribute to the overaccumulation of IAA in mutant plants. Moreover, we show that cyp83B1 mutants have lesion-mimic phenotypes, suggesting that multiple stress pathways are activated by loss of CYP83B1 function.

Research has been conducted on the tryptophan-shifted mutant of phosphofructokinase from Bacillus stearothermophilus. The construction of this mutant with the fluorescence emission properties responsive to the binding of the allosteric ligands is described.

Research has been conducted on the amino acid binding domains of the tryptophanyl (TrpRS) and tryptophanyl-tRNA synthetases (TyrRS) of Bacillus stearothermophilus. The TrpRS residues mutation based on the identity of the TyrRS homologous positions has been investigated.

Fluorescence spectroscopy has been used to study single tryptophan mutants of apolipophorin-III from Locusta migratoria, apol.p-III, in discoidal lipoproteins of dimyristoylphosphatidylcholine. Helices 1, 4 and 5 appear to interact with the lipid surface, but helices 2 and 3 do not interact with the lipid. They may do it by taking on a different binding configuration from that in helices 1, 4 and 5.

An analysis of the triplet-state properties of several tryptophan analogues inserted in three nucleases of Staphylococcus is presented. Phosphorescence and optically detected magnetic resonance measurements have been done on the analogues 7-azatryptophan (7AW), 5-hydroxytryptophan (5HW) and 4-, 5-, and 6-fluorotryptophan (4FW, 5FW, 6FW). These analogues have been incorporated at position 140 of the wild-type nuclease, positions 66 and 140 of the V66W mutant and on the delta-137-149 fragment of the mutant.

Tryptophan (Trp) analogues have been inserted into Staphylococcus to study the guanidine-HCl induced unfolding of three types of nucleases. The three nucleases are the wild-type protein (WT), the V66W mutant and the delta-137-149 fragment of the mutant (V66W'). The Trp analogues used are 5-hydroxytryptophan (5HW), 7-azatryptophan (7AW), 4-fluorotryptophan (4FW), 5FW and 6FW. Results show that 5HW affects the stability of V66W' but not the WT nuclease. The 7AW analogue affects all the nucleases when substituted at positions 66 or 140. The three other analogues have negligible effect on the stability of the nucleases.

Tryptophan (Trp) analogues have been added into three nucleases of Staphylococcus to evaluate their use as intrinsic probes and their effect on the structure of the proteins. The nucleases are the the wild-type protein, its V66W mutant and the delta-137-149 fragment of the mutant. The wild-type protein has a single Trp at position 140, the V66W mutant has another Trp at position 66 and the delta-137-149 fragment has a Trp at position 66 only. The Trp analogues used include 5HW, 7AW, 4-fluorotryptophan (4FW), 5FW and 6FW.

A study was conducted to describe residual structures in an unfolfed form of yeast phosphoglycerate kinase. Fluorescence measurements were determined with a 2 mu-M protein concentration after incubation at 6 degrees C in various concentrations of Gdm-Cl or urea. A scattering solution of Ludox was utilized to record the instrumental function at the emission wavelength. Results showed that the decay of the wild-type protein was induced by two exponential terms.

The regions of the lac repressor protein involved in conformational changes in response to ligand binding in Escherichia coli were determined. Mutant repressor proteins with single tryptophans were produced by mutating each of the two native tryptophan residues to tyrosine and altering the residue of interest to tryptophan. Findings showed that in the investigated areas of the lac repressor, the inducer-bound form is different from the conformation of the unliganded form.

Bacillus subtilis strains with temperature-sensitive mutant form of tryptophanyl-tRNA synthetase, encoded by the trpS1 allele, were confirmed to generate elevated levels of the tryptophan pathway enzymes, when grown at high temperatures in the presence of excess L-tryptophan. Also, the expression of two reporter gene fusions, trpE'-'lacZ and trpG'-'lacZ, also increased under these conditions.

The ability of trp (ribonucleotide) RNA-binding attenuation protein (TRAP) of Bacillus subtilis to bind with RNA and the resulting formation of TRAP-RNA complexes is dependent on the number of GAG repeats. The overall stability of the TRAP-RNA complexes is dependent on the specific nucleotide sequence of the spacers that separate the GAG repeats. The TRAP binding site to the RNA duplex is composed of single stranded RNA with 11 GAG repeats that are separated by two UU or AU spacers.

Study of deletion mutagenesis and expression in human tryptophan hydroxylase (TPH) reveals the enzyme to comprise a C-terminal region, a catalytic core and an N-terminal regulatory domain. A maltose-binding protein expresses TPH in Escherichia coli. TPH belongs to an aromatic amino acid hydroxylase family and is dependent on pterin.

The structural genes of Lactococcus lactis subsp. lactis IL1403 involved in tryptophan biosynthesis were cloned and characterized. The seven trp genes span 7,968 bp and are organized in the order trpEGDCFBA. Three pairs of genes, trpG-trpD, trpC-trpF and trpB-trpA, overlap, and intercistronic spacing exists between the trpE-trpG, trpD-trpC and trpF-trpB gene pairs. It seems unlikely that an attenuation mechanism regulates tryptophan biosynthesis in L. lactis subsp. lactis, since no potential leader peptide was detected.

Two tryptophanyl-tRNAs of Spiroplasma citri were analyzed. The first tRNA(super Trp) species has a CCA anticodon and is able to read the universal UGG tryptophan codon, while the second has a U*CA anticodon that is able to pair not only with UGA but also with UGG. It was found that the sequences of these two tRNA(super Trp) species show high similarity and that the corresponding genes are arranged in a single transcription unit.

A study was done on the solution structure of the DNA-binding unit of Myb protooncogene. It was shown that the c-myb protooncogene product has three imperfect tandem repeats of 51 and 52 amino acids containing three conserved tryptophans spaced 18 or 19 amino acids apart. The third repeat has three well-defined helices maintained by a hydrophobic core that has three tryptophans and two histidines. Helices two and three resemble that of the helix-turn-helix motif.

The B. subtilis MtrAGTP cyclohydrolase I was sequenced and compared to rat GTP cyclohydrolase I. Results showed 50% homology which increased to 65% upon inclusion of the conservative amino acid sequences. Expression of the B. subtilis mtrA, which codes for cyclohydroxylase in Escherichia coli further shows that it encodes GTP cyclohydrolase I due to a detected increase activity of the enzyme. The second gene of the bicistronic mtrAB operon, mtrB, regulates the termination oftranscription control of the tryptophan-producing gene cluster in E. coli, in contrast to previous reports.