Hypothetical Proteins Of Unknown Function Research Articles

Structure of Mycobacterium tuberculosis Rv2714, a representative of a duplicated gene family in Actinobacteria.

The gene Rv2714 from Mycobacterium tuberculosis, which codes for a hypothetical protein of unknown function, is a representative member of a gene family that is largely confined to the order Actinomycetales of Actinobacteria. Sequence analysis indicates the presence of two paralogous genes in most mycobacterial genomes and suggests that gene duplication was an ancient event in bacterial evolution. The crystal structure of Rv2714 has been determined at 2.6 A resolution, revealing a trimer in which the topology of the protomer core is similar to that observed in a functionally diverse set of enzymes, including purine nucleoside phosphorylases, some carboxypeptidases, bacterial peptidyl-tRNA hydrolases and even the plastidic form of an intron splicing factor. However, some structural elements, such as a beta-hairpin insertion involved in protein oligomerization and a C-terminal alpha-helical domain that serves as a lid to the putative substrate-binding (or ligand-binding) site, are only found in Rv2714 bacterial homologues and represent specific signatures of this protein family.

Molecular Characterization of Tetracycline-Resistant Genes and Integrons from Avirulent Strains ofEscherichia coliIsolated from Catfish

A study was undertaken to investigate the occurrence of tetracycline-resistant genes and to characterize the integrons present in Escherichia coli isolated from catfish. Sixty-three tetracycline-resistant E. coli strains were isolated from the intestinal contents of 407 farm-raised catfish. All strains were resistant to multiple antibiotics. A polymerase chain reaction (PCR) assay detected tetA in the DNA of 15 of 63 (25.0%) isolates by amplifying a PCR amplicon measuring 957 bp. Oligonucleotide primers targeting a 436-bp region of tetB successfully amplified a PCR amplicon from 47 of 63 (77.0%) isolates, indicating that tetB was predominant. Oligonucleotide primers specific for tetC amplified a 589-bp PCR amplicon from 3 of 63 (5%) isolates. Eleven (17.0%) of the isolates contained both tetA and tetB genes. Class I integrons amplified from the genomic DNA of 14 of 63 (22.0%) isolates measured 1.6 and 1.8 kb. Sequence analysis of the 1.6 kb integrons indicated the presence of three different gene cassettes: a dfrA12, conferring resistance to trimethoprim; an open reading frame, orfF, a hypothetical protein of unknown function; and aadA2, conferring resistance to aminoglycosides. Sequence analysis of the 1.8-kb integron indicated the presence of dfrA17 and aadA5. PCR assays for the detection of the six predominant virulence genes failed to amplify any genes from the genomic DNA. Pulsed-field gel electrophoresis using XbaI identified 16 distinct macro restriction patterns among the 63 isolates. The dendrogram analysis indicated that the DNA from 4 of 16 isolates had a similarity index of 90.0%. Our results indicate that the use of oxytetracycline and Romet 30 (sulfadimethoxine and ormetoprim) in farm-raised catfish may select for multiple antibiotic-resistant E. coli that could serve as a reservoir of tetracycline, trimethoprim, and aminoglycoside resistance genes.

Identification of the Cellobiose 2-Epimerase Gene in the Genome ofBacteroides fragilisNCTC 9343

Cellobiose 2-epimerase (CE, EC 5.1.3.11) catalyzes the reversible epimerization of cellobiose to 4-O-beta-D-glucopyranosyl-D-mannose. In this study, we found a CE gene in the genome sequence of non-cellulolytic Bacteroides fragilis NCTC 9343. The recombinant enzyme, expressed in Escherichia coli cells, catalyzed a hydroxyl stereoisomerism at the C-2 positions of the reducing terminal glucose and at the mannose moiety of cello-oligosaccharides, lactose, beta-mannobiose (4-O-beta-D-mannopyranosyl-D-mannose), and globotriose [O-alpha-D-galactopyranosyl-(1-->4)-O-beta-D-galactopyranosyl-(1-->4)-D-glucose]. The CE from B. fragilis showed less than 40% identity to reported functional CEs. It exhibited 44-63% identities to N-acyl-D-glucosamine 2-epimerase-like hypothetical proteins of unknown function in bacterial genome sequences of the phyla Firmicutes, Bacteroidetes, Proteobacteria, Chloroflexi, and Verrucomicrobia. On the other hand, it showed less than 26% identity to functional N-acyl-D-glucosamine 2-epimerases. Based on the amino acid homology and phylogenetic positions of the functional epimerases, we emphasize that many genes for putative N-acyl-D-glucosamine 2-epimerases and related hypothetical proteins of unknown function reported to date in the bacterial genomes should be annotated as CE-like proteins or putative CEs.

The time course of the transcriptomic response of Sinorhizobium meliloti1021 following a shift to acidic pH

BackgroundThe symbiotic soil bacterium Sinorhizobium meliloti often has to face low pH in its natural habitats. To identify genes responding to pH stress a global transcriptional analysis of S. meliloti strain 1021 following a pH shift from pH 7.0 to pH 5.75 was carried out. In detail, oligo-based whole genome microarrays were used in a time course experiment. The monitoring period covered a time span of about one hour after the pH shift. The obtained microarray data was filtered and grouped by K-means clustering in order to obtain groups of genes behaving similarly concerning their expression levels throughout the time course.ResultsThe results display a versatile response of S. meliloti 1021 represented by distinct expression profiles of subsets of genes with functional relation. The eight generated clusters could be subdivided into a group of four clusters containing genes that were up-regulated and another group of four clusters containing genes that were down-regulated in response to the acidic pH shift. The respective mean expression progression of the four up-regulated clusters could be described as (i) permanently and strong, (ii) permanently and intermediate, (iii) permanently and progressive, and (iv) transiently up-regulated. The expression profile of the four down-regulated clusters could be characterized as (i) permanently, (ii) permanently and progressive, (iii) transiently, and (iv) ultra short down-regulated. Genes coding for proteins with functional relation were mostly cumulated in the same cluster, pointing to a characteristic expression profile for distinct cellular functions. Among the strongest up-regulated genes lpiA, degP1, cah, exoV and exoH were found. The most striking functional groups responding to the shift to acidic pH were genes of the exopolysaccharide I biosynthesis as well as flagellar and chemotaxis genes. While the genes of the exopolysaccharide I biosynthesis (exoY, exoQ, exoW, exoV, exoT, exoH, exoK exoL, exoO, exoN, exoP) were up-regulated, the expression level of the flagellar and chemotaxis genes (visR, motA, flgF, flgB, flgC, fliE, flgG, flgE, flgL, flbT, mcpU) simultaneously decreased in response to acidic pH. Other responding functional groups of genes mainly belonged to nitrogen uptake and metabolism (amtB, nrtB, nirB, nirD), methionine metabolism (metA, metF, metH, metK, bmt and ahcY) as well as ion transport systems (sitABCD, phoCD). It is noteworthy, that several genes coding for hypothetical proteins of unknown function could be identified as up-regulated in response to the pH shift.ConclusionIt was shown that the short term response to acidic pH stress does not result in a simple induction or repression of genes, but in a sequence of responses varying in their intensity over time. Obviously, the response to acidic pH is not based on a few specific genes, but involves whole sets of genes associated with various cellular functions.

Comparative genomics of Helicobacter pylori

Genomic sequences have been determined for a number of strains of Helicobacter pylori (H. pylori) and related bacteria. With the development of microarray analysis and the wide use of subtractive hybridization techniques, comparative studies have been carried out with respect to the interstrain differences between H. pylori and inter-species differences in the genome of related bacteria. It was found that the core genome of H. pylori constitutes 1111 genes that are determinants of the species properties. A great pool of auxillary genes are mainly from the categories of cag pathogenicity islands, outer membrane proteins, restriction-modification system and hypothetical proteins of unknown function. Persistence of H. pylori in the human stomach leads to the diversification of the genome. Comparative genomics suggest that a host jump has occurs from humans to felines. Candidate genes specific for the development of the gastric diseases were identified. With the aid of proteomics, population genetics and other molecular methods, future comparative genomic studies would dramatically promote our understanding of the evolution, pathogenesis and microbiology of H. pylori.

Determination of a transcriptional regulator-like gene involved in biosynthesis of elsinochrome phytotoxin by the citrus scab fungus, Elsinoë fawcettii

Elsinochromes are nonhost-selective, light-activated, polyketide-derived toxins produced by many phytopathogenic Elsinoë species. We recently showed that the polyketide synthase-encoding gene EfPKS1 is essential for elsinochrome biosynthesis in the citrus scab fungus Elsinoë fawcettii. Sequence analysis beyond the EfPKS1 gene identified nine putative ORFs: four genes, designated RDT1, TSF1, PRF1 and ECT1, all encode polypeptides likely to have biosynthetic or efflux functions; five additional genes, OXR1 and EfHP1 to EfHP4, encode hypothetical proteins of unknown function. Northern-blot analysis revealed that expression of these genes in E. fawcettii was not completely correlated with accumulation of elsinochromes under nitrogen limitation, alkaline pH or high concentrations of glucose. Targeted disruption of the TSF1 gene, encoding a putative transcriptional activator, yielded fungal mutants unable to produce elsinochromes, and defective in both conidiation and expression of RDT1, EfPKS1, PRF1 and EfHP1, whereas expression of RDT1, TSF1, PRF1 and ECT1 was nearly abolished in EfPKS1-disrupted mutants. By contrast, expression of OXR1, EfHP2 and EfHP3 was not affected by disrupting either EfPKS1 or TSF1. Taken together, the results indicate that in addition to polyketide synthase, the products of TSF1 and other adjacent genes may also play a crucial role in elsinochrome production.

Structural organization of the glnBA region of the Azospirillum brasilense genome

The Azospirillum brasilense genomic region containing the glnBA genes was previously cloned in a broad-host range plasmid named pAB441. Previous results from our laboratory have shown that A. brasilense spontaneous mutants resistant to ethylenediamine carrying this plasmid had no nitrogenase activity. The 19 kb insert of this plasmid was fully sequenced and no other gene potentially involved with nitrogen fixation was identified, nor any gene potentially involved in the regulation of nif genes expression. Apart from glnBA, this region contains several genes involved with different functions: assisting protein folding and degradation, DNA organization, electron transport and energy conversion and conserved hypothetical proteins of unknown function. Since previous data on the literature showed that mutation of clpX gene of A. brasilense resulted in higher nitrogenase activity, we hypothesize that higher expression of the clpX gene from the plasmid pAB441 may be involved with Nif − phenotype of the A. brasilense mutant strains.

The recovery of Mycobacterium avium subspecies paratuberculosis from the intestine of infected ruminants for proteomic evaluation

Johne's disease is a slowly developing intestinal disease, primarily of ruminants, caused by Mycobacterium avium subspecies paratuberculosis. The disease contributes to significant economic losses worldwide in agricultural industry. Analysis of bacterial proteomes isolated directly from infected animals can provide important information about the repertoire of proteins present during infection and disease progression. In this study, M. avium subspecies paratuberculosis has been extracted from Johne's disease-infected cattle and goat intestinal tissue sections in a manner compatible with direct 2-DE proteomic analysis for comparison with in vitro-cultured bacteria. M. avium subspecies paratuberculosis was harvested from the submucosa and mucosa of intestinal sections and enriched from macerated tissue by hypotonic lysis, sonication and centrifugation through a viscosity gradient. Subsequent comparison of the proteomes of the in vivo- and in vitro-derived bacteria identified a number of proteins that were differentially expressed. Among them, a number of hypothetical proteins of unknown function and a hypothetical fatty acyl dehydrogenase (FadE3_2) and 3-hydroxyacyl-CoA dehydrogenase, possibly important for in vivo metabolism, utilising the pathway for the β-oxidation of fatty acids.

Structure of a putative acetyltransferase (PA1377) from Pseudomonas aeruginosa.

Gene PA1377 from Pseudomonas aeruginosa encodes a 177-amino-acid conserved hypothetical protein of unknown function. The structure of this protein (termed pitax) has been solved in space group I222 to 2.25 A resolution. Pitax belongs to the GCN5-related N-acetyltransferase family and contains all four sequence motifs conserved among family members. The beta-strand structure in one of these motifs (motif A) is disrupted, which is believed to affect binding of the substrate that accepts the acetyl group from acetyl-CoA.

The hypothetical protein Atu4866 from Agrobacterium tumefaciens adopts a streptavidin‐like fold

Atu4866 is a 79-residue conserved hypothetical protein of unknown function from Agrobacterium tumefaciens. Protein sequence alignments show that it shares > or =60% sequence identity with 20 other hypothetical proteins of bacterial origin. However, the structures and functions of these proteins remain unknown so far. To gain insight into the function of this family of proteins, we have determined the structure of Atu4866 as a target of a structural genomics project using solution NMR spectroscopy. Our results reveal that Atu4866 adopts a streptavidin-like fold featuring a beta-barrel/sandwich formed by eight antiparallel beta-strands. Further structural analysis identified a continuous patch of conserved residues on the surface of Atu4866 that may constitute a potential ligand-binding site.

Complete Genomic Characterization of a Pathogenic A.II Strain of Francisella tularensis Subspecies tularensis

Francisella tularensis is the causative agent of tularemia, which is a highly lethal disease from nature and potentially from a biological weapon. This species contains four recognized subspecies including the North American endemic F. tularensis subsp. tularensis (type A), whose genetic diversity is correlated with its geographic distribution including a major population subdivision referred to as A.I and A.II. The biological significance of the A.I – A.II genetic differentiation is unknown, though there are suggestive ecological and epidemiological correlations. In order to understand the differentiation at the genomic level, we have determined the complete sequence of an A.II strain (WY96-3418) and compared it to the genome of Schu S4 from the A.I population. We find that this A.II genome is 1,898,476 bp in size with 1,820 genes, 1,303 of which code for proteins. While extensive genomic variation exists between “WY96” and Schu S4, there is only one whole gene difference. This one gene difference is a hypothetical protein of unknown function. In contrast, there are numerous SNPs (3,367), small indels (1,015), IS element differences (7) and large chromosomal rearrangements (31), including both inversions and translocations. The rearrangement borders are frequently associated with IS elements, which would facilitate intragenomic recombination events. The pathogenicity island duplicated regions (DR1 and DR2) are essentially identical in WY96 but vary relative to Schu S4 at 60 nucleotide positions. Other potential virulence-associated genes (231) varied at 559 nucleotide positions, including 357 non-synonymous changes. Molecular clock estimates for the divergence time between A.I and A.II genomes for different chromosomal regions ranged from 866 to 2131 years before present. This paper is the first complete genomic characterization of a member of the A.II clade of Francisella tularensis subsp. tularensis.

Solution structure of HI1506, a novel two‐domain protein from Haemophilus influenzae

HI1506 is a 128-residue hypothetical protein of unknown function from Haemophilus influenzae. It was originally annotated as a shorter 85-residue protein, but a more detailed sequence analysis conducted in our laboratory revealed that the full-length protein has an additional 43 residues on the C terminus, corresponding with a region initially ascribed to HI1507. As part of a larger effort to understand the functions of hypothetical proteins from Gram-negative bacteria, and H. influenzae in particular, we report here the three-dimensional solution NMR structure for the corrected full-length HI1506 protein. The structure consists of two well-defined domains, an alpha/beta 50-residue N-domain and a 3-alpha 32-residue C-domain, separated by an unstructured 30-residue linker. Both domains have positively charged surface patches and weak structural homology with folds that are associated with RNA binding, suggesting a possible functional role in binding distal nucleic acid sites.

Group A streptococcus cell‐associated pathogenic proteins as revealed by growth in hyaluronic acid‐enriched media

Group A streptococcus (GAS), also know as Streptococcus pyogenes, is a human pathogen and can cause several fatal invasive diseases such as necrotising fasciitis, the so-called flesh-eating disease, and toxic shock syndrome. The destruction of connective tissue and the hyaluronic acid (HA) therein, is a key element of GAS pathogenesis. We therefore propagated GAS in HA-enriched growth media in an attempt to create a simple biological system that could reflect some elements of GAS pathogenesis. Our results show that several recognised virulence factors were up-regulated in HA-enriched media, including the M1 protein, a collagen-like surface protein and the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase, which has been shown to play important roles in streptococcal pathogenesis. Interestingly, two hypothetical proteins of unknown function were also up-regulated and detailed bioinformatics analysis showed that at least one of these hypothetical proteins is likely to be involved in pathogenesis. It was therefore concluded that this simple biological system provided a valuable tool for the identification of potential GAS virulence factors.

A Novel Deaminase Involved in Chloronitrobenzene and Nitrobenzene Degradation with Comamonas sp. Strain CNB-1

Comamonas sp. strain CNB-1 degrades nitrobenzene and chloronitrobenzene via the intermediates 2-aminomuconate and 2-amino-5-chloromuconate, respectively. Deamination of these two compounds results in the release of ammonia, which is used as a source of nitrogen for bacterial growth. In this study, a novel deaminase was purified from Comamonas strain CNB-1, and the gene (cnbZ) encoding this enzyme was cloned. The N-terminal sequence and peptide fingerprints of this deaminase were determined, and BLAST searches revealed no match with significant similarity to any functionally characterized proteins. The purified deaminase is a monomer (30 kDa), and its V(max) values for 2-aminomuconate and 2-amino-5-chloromuconate were 147 micromol x min(-1) x mg(-1) and 196 micromol x min(-1) x mg(-1), respectively. Its catalytic products from 2-aminomuconate and 2-amino-5-chloromuconate were 2-hydroxymuconate and 2-hydroxy-5-chloromuconate, respectively, which are different from those previously reported for the deaminases of Pseudomonas species. In the catalytic mechanism proposed, the alpha-carbon and nitrogen atoms (of both 2-aminomuconate and 2-amino-5-chloromuconate) were simultaneously attacked by a hydroxyl group and a proton, respectively. Homologs of cnbZ were identified in the genomes of Bradyrhizobium japonicum, Rhodopseudomonas palustris, and Roseiflexus sp. strain RS-1; these genes were previously annotated as encoding hypothetical proteins of unknown function. It is concluded that CnbZ represents a novel enzyme that deaminates xenobiotic compounds and/or alpha-amino acids.

Identification of a pyridoxine (pyridoxamine) 5′-phosphate oxidase from Arabidopsis thaliana

Pyridoxine (pyridoxamine) 5′-phosphate oxidase (PPOX) catalyzes the oxidative conversion of pyridoxamine 5′-phosphate (PMP) or pyridoxine 5′-phosphate (PNP) to pyridoxal 5′-phosphate (PLP). The At5g49970 gene of Arabidopsis thaliana shows homology to PPOX’s from a number of organisms including the Saccharomyces cerevisiae PDX3 gene. A cDNA corresponding to putative A. thaliana PPOX ( AtPPOX) was obtained using reverse transcriptase-polymerase chain reaction and primers landing at the start and stop codons of At5g49970. The putative AtPPOX is 530 amino acid long and predicted to contain three distinct parts: a 64 amino acid long N-terminal putative chloroplast transit peptide, followed by a long Yjef_N domain of unknown function and a C-terminal Pyridox_oxidase domain. Recombinant proteins representing the C-terminal domain of AtPPOX and AtPPOX without transit peptide were expressed in E. coli and showed PPOX enzyme activity. The PDX3 knockout yeast deficient in PPOX activity exhibited sensitivity to oxidative stress. Constructs of AtPPOX cDNA of different lengths complemented the PDX3 knockout yeast for oxidative stress. The role of the Yjef_N domain of AtPPOX was not determined, but it shows homology with a number of conserved hypothetical proteins of unknown function.

Identification of functional subclasses in the DJ-1 superfamily proteins.

Genomics has posed the challenge of determination of protein function from sequence and/or 3-D structure. Functional assignment from sequence relationships can be misleading, and structural similarity does not necessarily imply functional similarity. Proteins in the DJ-1 family, many of which are of unknown function, are examples of proteins with both sequence and fold similarity that span multiple functional classes. THEMATICS (theoretical microscopic titration curves), an electrostatics-based computational approach to functional site prediction, is used to sort proteins in the DJ-1 family into different functional classes. Active site residues are predicted for the eight distinct DJ-1 proteins with available 3-D structures. Placement of the predicted residues onto a structural alignment for six of these proteins reveals three distinct types of active sites. Each type overlaps only partially with the others, with only one residue in common across all six sets of predicted residues. Human DJ-1 and YajL from Escherichia coli have very similar predicted active sites and belong to the same probable functional group. Protease I, a known cysteine protease from Pyrococcus horikoshii, and PfpI/YhbO from E. coli, a hypothetical protein of unknown function, belong to a separate class. THEMATICS predicts a set of residues that is typical of a cysteine protease for Protease I; the prediction for PfpI/YhbO bears some similarity. YDR533Cp from Saccharomyces cerevisiae, of unknown function, and the known chaperone Hsp31 from E. coli constitute a third group with nearly identical predicted active sites. While the first four proteins have predicted active sites at dimer interfaces, YDR533Cp and Hsp31 both have predicted sites contained within each subunit. Although YDR533Cp and Hsp31 form different dimers with different orientations between the subunits, the predicted active sites are superimposable within the monomer structures. Thus, the three predicted functional classes form four different types of quaternary structures. The computational prediction of the functional sites for protein structures of unknown function provides valuable clues for functional classification.

The Crystal Structure of Rv0813c from Mycobacterium tuberculosis Reveals a New Family of Fatty Acid-Binding Protein-Like Proteins in Bacteria

The gene Rv0813c from Mycobacterium tuberculosis, which codes for a hypothetical protein of unknown function, is conserved within the order Actinomycetales but absent elsewhere. The crystal structure of Rv0813c reveals a new family of proteins that resemble the fatty acid-binding proteins (FABPs) found in eukaryotes. Rv0813c adopts the 10-stranded beta-barrel fold typical of FABPs but lacks the double-helix insert that covers the entry to the binding site in the eukaryotic proteins. The barrel encloses a deep cavity, at the bottom of which a small cyclic ligand was found to bind to the hydroxyl group of Tyr192. This residue is part of a conserved Arg-X-Tyr motif much like the triad that binds the carboxylate group of fatty acids in FABPs. Most of the residues forming the internal surface of the cavity are conserved in homologous protein sequences found in CG-rich prokaryotes, strongly suggesting that Rv0813c is a member of a new family of bacterial FABP-like proteins that may have roles in the recognition, transport, and/or storage of small molecules in the bacterial cytosol.

Structure of a conserved hypothetical protein SA1388 from S. aureus reveals a capped hexameric toroid with two PII domain lids and a dinuclear metal center

BackgroundThe protein encoded by the SA1388 gene from Staphylococcus aureus was chosen for structure determination to elucidate its domain organization and confirm our earlier remote homology based prediction that it housed a nitrogen regulatory PII protein-like domain. SA1388 was predicted to contain a central PII-like domain and two flanking regions, which together belong to the NIF3-like protein family. Proteins like SA1388 remain a poorly studied group and their structural characterization could guide future investigations aimed at understanding their function.ResultsThe structure of SA1388 has been solved to 2.0Å resolution by single wavelength anomalous dispersion phasing method using selenium anomalous signals. It reveals a canonical NIF3-like fold containing two domains with a PII-like domain inserted in the middle of the polypeptide. The N and C terminal halves of the NIF3-like domains are involved in dimerization, while the PII domain forms trimeric contacts with symmetry related monomers. Overall, the NIF3-like domains of SA1388 are organized as a hexameric toroid similar to its homologs, E. coli ybgI and the hypothetical protein SP1609 from Streptococcus pneumoniae. The openings on either side of the toroid are partially covered by trimeric "lids" formed by the PII domains. The junction of the two NIF3 domains has two zinc ions bound at what appears to be a histidine rich active site. A well-defined electron density corresponding to an endogenously bound ligand of unknown identity is observed in close proximity to the metal site.ConclusionSA1388 is the third member of the NIF3-like family of proteins to be structurally characterized, the other two also being hypothetical proteins of unknown function. The structure of SA1388 confirms our earlier prediction that the inserted domain that separates the two NIF3 domains adopts a PII-like fold and reveals an overall capped toroidal arrangement for the protein hexamer. The six PII-like domains form two trimeric "lids" that cap the central cavity of the toroid on either side and provide only small openings to allow regulated entry of small molecules into the occluded chamber. The presence of the electron density of the bound ligand may provide important clues on the likely function of NIF3-like proteins.

The molecular structure of Rv1873, a conserved hypothetical protein from Mycobacterium tuberculosis, at 1.38 A resolution.

The X-ray crystal structure of the gene product encoded by open reading frame Rv1873 of Mycobacterium tuberculosis has been determined by single isomorphous replacement with anomalous scattering (SIRAS) phasing techniques at 1.38 A resolution from monoclinic crystals with unit-cell parameters a = 33.44, b = 31.63, c = 53.19 A, beta = 90.8 degrees. The 16.2 kDa Rv1873 is a monomer that adopts a primarily alpha-helical fold with limited structural similarity to previously determined tertiary structures. It has been annotated as a conserved hypothetical protein of unknown function and is classified by the Clusters of Orthologous Groups (COG) database as belonging to COG5579. The three-dimensional structure of the Rv1873 gene product reveals limited similarity to a repeated motif that is found in a variety of other proteins. While not a novel fold, it serves as a model for orthologues predicted to be related by sequence and it is hoped that knowledge of the structure of Rv1873 will aid in determining a possible function for this protein.

Crystal structure of TM1367 from Thermotoga maritima at 1.90 Å resolution reveals an atypical member of the cyclophilin (peptidylprolyl isomerase) fold

Crystal structure of TM1367 from <i>Thermotoga maritima</i> at 1.90 Å resolution reveals an atypical member of the cyclophilin (peptidylprolyl isomerase) fold