Rv0787A Family assigned · medium auto-curated

H37Rv Rv0787A · MTBC0 - · 79 aa · 882524–882763 H37Rv (+) · RefSeq YP_177755.1

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Annotation: from legacy to revised

Legacy (H37Rv / Mycobrowser)hypothetical protein
MTBC0 PGAP re-annotation
Revised (this work)Contains PurS (PF02700.20) domain(s); putative function inferred from the domain architecture.
Functional category (TubercuList)conserved hypotheticals

Auto-curated: this verdict and function were generated by rules from PGAP + Pfam + Foldseek and have not been hand-reviewed.

Annotated on the H37Rv protein: this gene has no 1:1 ancestral MTBC0 anchor (PE/PPE, paralogue, IS element, or otherwise unanchored CDS).

In the literature (TB corpus sweep) never studied

No publication in PubMed mentions this gene in its title or abstract — not under its H37Rv locus tag, nor under any of its ortholog identifiers (M. bovis, M. marinum, M. smegmatis, M. leprae, M. abscessus). The atlas annotation rests on sequence/structure evidence, not on a primary study of this gene.

A verified absence of literature is itself information: it flags an annotation with no primary study behind it. This distinguishes a gene that is dark because nobody has looked from one that is dark despite having been studied. Source: PubMed (whole), MULTI-ALIAS sweep: H37Rv locus tag AND every ortholog identifier (M. bovis Mb…, M. marinum MMAR_…, M. smegmatis MSMEG_…, M. leprae ML…, M. abscessus MAB_…), each hit VERIFIED against the abstract text (word-boundary regex). phase73/phase75, 2026-07-13.

Genomic-neighbour overlap (structural caveat) co-directional · 2 % of gene

NeighbourpurQ (Rv0788, + strand)
Overlap4 bp, 2 % of this gene's length

co-directional overlap: ordinary (e.g. shared stop/start codons in an operon), not the Rv2438A-type artefact P20.1, derived from GFF3 gene coordinates, 2026-08-03.

CRISPRi vulnerability

Vulnerability index -12.29 (95% CI -14.15 to -10.46). A more negative index = more vulnerable to knockdown (better drug-target quality); indicative threshold VI ≤ -6 = highly vulnerable.

Quantitative CRISPRi knockdown, graded (finer than binary Tn-seq essentiality). Source: CRISPRi vulnerability index (Bosch 2021, pebble.rockefeller.edu).

Legacy record & comparison (Mycobrowser) ahead of Mycobrowser

Mycobrowser functionFunction unknown

Mycobrowser classes this locus among conserved hypotheticals; the atlas now assigns a functional handle (curated function (UniProt), EC number, COG category). Mycobrowser is no longer maintained, so its EC numbers predate recent nomenclature revisions (e.g. the 2018 EC 7 "translocase" class) — most EC differences are re-numberings of the same enzyme, not conflicts.

Orthologues (reciprocal best hits across mycobacteria)

M. bovis Mb0811 · 100.0% identity
M. leprae ML2219A · 84.8% identity
M. marinum MMAR_4898 · 93.7% identity
M. smegmatis MSMEG_5832 · 88.3% identity
M. orygis RJtmp_000834 · 100.0% identity
M. abscessus MAB_0697 · 71.8% identity

Reciprocal-best-hit orthologues (DIAMOND) against the Mycobrowser reference proteomes. A missing species is informative: e.g. a gene absent from M. leprae was likely lost in its reductive genome evolution. Locus tags link to Mycobrowser.

Curated reference (UniProt)

UniProt I6Y8S6 TrEMBL · unreviewed · Evidence at protein level
UniProt namePhosphoribosylformylglycinamidine synthase subunit PurS
EC (curated) EC 6.3.5.3
Curated functionPart of the phosphoribosylformylglycinamidine synthase complex involved in the purines biosynthetic pathway. Catalyzes the ATP-dependent conversion of formylglycinamide ribonucleotide (FGAR) and glutamine to yield formylglycinamidine ribonucleotide (FGAM) and glutamate. The FGAM synthase complex is composed of three subunits. PurQ produces an ammonia molecule by converting glutamine to glutamate. PurL transfers the ammonia molecule to FGAR to form FGAM in an ATP-dependent manner. PurS interacts with PurQ and PurL and is thought to assist in the transfer of the ammonia molecule from PurQ to Pur.

Functional vocabulary (eggNOG-mapper, orthology transfer)

COG category F Nucleotide transport and metabolism
Preferred namepurS
eggNOG descriptionPart of the phosphoribosylformylglycinamidine synthase complex involved in the purines biosynthetic pathway. Catalyzes the ATP-dependent conversion of formylglycinamide ribonucleotide (FGAR) and glutamine to yield formylglycinamidine ribonucleotide (FGAM) and glutamate. The FGAM synthase complex is composed of three subunits. PurQ produces an ammonia molecule by converting glutamine to glutamate. PurL transfers the ammonia molecule to FGAR to form FGAM in an ATP-dependent manner. PurS interacts with PurQ and PurL and is thought to assist in the transfer of the ammonia molecule from PurQ to PurL
Orthologous groupCOG1828
EC number EC 6.3.5.3
KEGG orthology K01952
KEGG pathways map00230, map01100, map01110, map01130
KEGG modules M00048

Orthology-based transfer (eggNOG 5.0.2, diamond). EC/KO/GO/CAZy are computed annotations, not manual curation; cross-check against the primary literature before treating a specific reaction as established.

Outgroup conservation (beyond the MTBC) Bacteria

Genus-wide presence (~53 non-MTBC Mycobacterium) present in 53/53 (100%) · mean identity 90.3% · 4/4 closest MTBAP relatives
conserved across the genus (present in 53/53 non-MTBC Mycobacterium genomes, incl. distant relatives) — an ancient core gene predating the genus radiation
Phylostratum (deepest detected homolog) MTBC-specific Mycobacterium Mycobacteriaceae Corynebacteriales Actinomycetia Bacteria
detected in 10/13 non-Mycobacterium reference genomes (down to Bacteria) · mean identity 69.0%
detected down to outside the phylum (Proteobacteria/Firmicutes controls) — a universally conserved, ancient bacterial gene

Two orthogonal outgroup signals. M. canettii (the immediate outgroup) gives a deep-divergence dN/dS (a low value confirms a constrained, real gene; shown as confident only at ≥8 substitutions, else flagged low-power). Genus-wide presence/absence (tblastn vs assembled non-MTBC genomes) places the gene on the ancient-core ↔ MTBC-specific axis: a gene absent even from the closest MTBAP relatives is a candidate MTBC-specific innovation (possible host-adaptation factor, to confirm by synteny). The phylostratum extends that axis outside the genus (tblastn vs 13 reference genomes spanning Mycobacteriaceae → Corynebacteriales → Actinomycetia → outside the phylum): it is the deepest clade in which a homolog is still detected, i.e. a proxy for gene age. Read it with the null model in mind: a shallow (young) stratum can also reflect homology-detection failure for short or fast-evolving ORFs, so it is a descriptive axis, not a proof of novelty.

Essentiality (transposon mutagenesis) essential

DeJesus 2017 callES · essential
What the call meansessential: insertions absent across the whole ORF
TA sites (Himar1) 2 in the ORF — 2 in the essential state, 0 growth-defect, 0 non-essential, 0 growth-advantage. Saturation 0.000, mean read count 0. A region of the protein devoid of TA sites is invisible to this assay: nothing can be inferred about it, in either direction.
CaveatStatistically thin call: only 2 TA (Himar1) sites in the whole ORF (atlas median 13; genes under 300 nt typically have very few). A DeJesus 2017 call built on so few independent observations is less robust than the same call on a longer gene, in either direction. Cross-check against the CRISPRi vulnerability index (independent of TA-site density) and, if this gene overlaps a neighbour (see Genomic-neighbour overlap section below), verify how many of its TA sites actually fall inside its own ORF. (P20.3)

Genome-wide Himar1 transposon essentiality in H37Rv (DeJesus 2017). An essential call (ES/ESD/GD) is strong, independent evidence that a "hypothetical" locus encodes a functional, selectively required gene — orthogonal to intra-species conservation.

Chemical-genetic target & druggability (PROSPECT) hypomorph tool strain

This gene is part of the PROSPECT collection of TetON transcriptional-knockdown (hypomorph) strains of essential M. tuberculosis genes, built as a sensitised background for chemical-genetic mechanism-of-action deconvolution. Being in the panel means the gene is an essential / vulnerable target for which a validated knockdown tool strain exists.

Hypomorph strainRv0787A-TetOn10.1 (TetON promoter 10)
Baseline knockdown fitness4.506 median doublings (across 6 screen pool(s)) — fewer doublings = stronger growth defect on knockdown
Used in target deconvolutionyes (informs phenotypic-cluster / MOA assignment)

Panel membership reflects essentiality/vulnerability and the availability of a genetic tool, not a specific molecular function; it never changes the verdict here. Source: Bond AN et al., Nat Commun 2025;16:9673 (doi:10.1038/s41467-025-64662-x); PROSPECT chemical-genetic platform.

Proteomics (mass spectrometry) detected

MS detectiondetected in 15 of 16 independent MS datasets
Integrated abundance606.0 ppm · rank 353/3519 (90.0th percentile)

Detection by mass spectrometry is direct, experimental evidence that the protein product exists — orthogonal to sequence conservation and to Tn-seq essentiality, and especially decisive for a "hypothetical" locus. Reproducible detection across several independent datasets (PaxDb) makes the existence claim robust; the integrated abundance places the protein in the proteome's dynamic range.

Physico-chemical properties (computed, ProtParam)

Length79 aa
Molecular weight8.6 kDa
Theoretical pI4.49
GRAVY-0.035 (hydrophilic)
Aliphatic index111.0
Aromaticity0.025
Instability index32.7 (stable)

Computed from the ancestral MTBC0 sequence with the ExPASy ProtParam method (Biopython). Descriptive biophysical context: a positive GRAVY flags a hydrophobic (often membrane) protein, a high instability index (>40) predicts a short in-vitro half-life, an extreme pI hints at compartment or binding partner.

Domains (Pfam, hmmscan --cut_ga)

PfamAccessioni-EvalueResiduesDescription
PurSPF02700.20 4.0e-244–74 Phosphoribosylformylglycinamidine (FGAM) synthase

Structural search (AlphaFold DB model, Foldseek vs PDB — genome-wide) pLDDT 95.8

PDB hitprobTM-scoreE-valueDescription
1t4a-assembly1_A 1.00 0.89 3.4e-09 sig 1t4a-assembly1_A Structure of B. Subtilis PurS C2 Crystal Form
2yx5-assembly1_A 1.00 0.83 1.0e-07 sig 2yx5-assembly1_A Crystal Structure of Methanocaldococcus jannaschii PurS, One of the Subunits of Formylglycinamide Ribonucleotide Amidotransferase in the Purine Biosynthetic Pathway
1gtd-assembly1_B 1.00 0.82 2.0e-05 sig 1gtd-assembly1_B NORTHEAST STRUCTURAL GENOMICS CONSORTIUM (NESG ID TT50) STRUCTURE OF MTH169, THE PURS SUBUNIT OF FGAM SYNTHETASE
1vq3-assembly1_C 1.00 0.82 2.3e-05 sig 1vq3-assembly1_C Crystal structure of Phosphoribosylformylglycinamidine synthase, purS subunit (EC 6.3.5.3) (TM1244) from Thermotoga maritima at 1.90 A resolution
2zw2-assembly1_B 1.00 0.82 1.7e-05 sig 2zw2-assembly1_B Crystal Structure of Formylglycinamide Ribonucleotide Amidotransferase III from SULFOLOBUS TOKODAII (STPURS)

Foldseek search of the AlphaFold DB model (mean pLDDT 95.8, gated at 70) against the PDB — a genome-wide extension of the ESMFold dark-gene search that also covers proteins beyond the single-sequence length limit. Confident structural neighbours (E < 0.01) shown.

Genomic context (neighbours & predicted operon) operon of 2

Upstream (5' on genome)Rv0787 (+ strand, 105 bp gap)
Downstream (3' on genome)purQ (+ strand, -4 bp gap)
Predicted operon Rv0787A · purQ

Neighbours from the H37Rv annotation (+ strand). The operon is predicted by co-directional intergenic distance (same strand, gaps ≤50 bp) — a transcription-unit hypothesis, not a mapped TSS. For a "hypothetical", co-transcription with a characterised operon is a concrete functional lead (complements the STRING neighborhood channel below).

Transcriptional regulation (signed TRN: ChIP-seq + TFOE)

Regulated by (1 TF) Rv1353c (activates)

Regulatory edges from the ISB signed transcriptional regulatory network (TF ChIP-seq binding, Minch 2015 + TF-overexpression response, Rustad 2014). An edge is regulatory evidence (binding and/or expression change), not necessarily direct. For a "hypothetical", membership in a known regulon (e.g. DosR dormancy, PhoP virulence) is a strong physiological-context lead.

Functional interaction network (STRING v12, guilt-by-association)

Explore full network →

Node colour = verdict, dashed = hypothetical; edge colour = evidence (green experimental, orange genomic-context, grey co-expression), width ∝ score. Click a partner to open its page; "Explore full network" to walk the graph.

Closest characterised functional partner: purQ (phosphoribosylformylglycinamidine synthase), high confidence from genomic context alone (score 1000 excluding text-mining). This association is the citable seed of a function hypothesis for this hypothetical protein.

PartnerProductScoreNo text-miningChannels (≥400)
Rv0788 purQ exp phosphoribosylformylglycinamidine synthase 999 1000 ctx neighborhood:882 cooccurence:764 coexpression:863 experimental:790 database:900 textmining:590
Rv0803 purL exp phosphoribosylformylglycinamidine synthase 2 999 999 ctx cooccurence:767 coexpression:858 experimental:790 database:900 textmining:417
Rv0809 purM exp phosphoribosylformylglycinamidine cyclo-ligase PurM 991 989 coexpression:857 database:900
Rv0956 purN exp phosphoribosylglycinamide formyltransferase PurN 993 986 coexpression:843 database:900 textmining:576
Rv0389 purT exp phosphoribosylglycinamide formyltransferase PurT 929 908 database:900
Rv0808 purF amidophosphoribosyltransferase 910 894 coexpression:858
Rv0772 purD phosphoribosylamine--glycine ligase 913 886 coexpression:850
Rv0780 purC phosphoribosylaminoimidazole-succinocarboxamide synthase 910 883 coexpression:857
Rv3276c purK 5-(carboxyamino)imidazole ribonucleotide synthase 911 879 coexpression:840
Rv0957 purH bifunctional phosphoribosylaminoimidazolecarboxamide formyltransferase/inosinemonophosphate cyclohydrolase 888 871 coexpression:856
Rv3275c purE 5-(carboxyamino)imidazole ribonucleotide mutase 886 865 coexpression:854
Rv0777 purB adenylosuccinate lyase PurB 870 830 coexpression:778
Rv0787 hyp hypothetical protein 770 770 ctx neighborhood:769
Rv0786c hyp hypothetical protein 714 714 ctx neighborhood:713
Rv0357c purA adenylosuccinate synthetase 608 489 coexpression:425

STRING combines evidence channels (neighborhood, fusion, cooccurrence, coexpression, experimental, database, text-mining) into a 0–1000 score. The ctx badge marks edges carried by the genomic-context channels (conserved neighborhood, fusion, phylogenetic co-occurrence), which are independent of orthology and structure and the strongest signal for an unknown gene. The exp badge marks an experimentally-supported partner (measured interaction, experimental/database channel ≥400) as opposed to a purely predicted one — but note that the M. tuberculosis experimental interactome is dominated by a noisy bacterial-two-hybrid screen, so a strong measured link that contradicts the operon/localisation context is likely a false positive. The no text-mining column recomputes the score from data alone, so a link that does not depend on the literature is visible. Association is a function hypothesis, not proof: corroborate with the operon context and the primary literature before assigning a function.

Evidence

  • Annotation from H37Rv (no MTBC0 1:1 anchor; H37Rv protein used): hypothetical protein
  • Pfam (hmmscan --cut_ga): PurS PF02700.20 (E=4e-24)
  • (auto-curated by rules from PGAP + Pfam + Foldseek; not hand-reviewed)

Sources

  • Ancestral sequence & coordinates: Harrison LB et al. (2024), An imputed ancestral reference genome for the MTBC, doi:10.1101/2023.09.07.556366
  • Product annotation: NCBI PGAP on MTBC0; legacy from H37Rv NC_000962.3 (RefSeq YP_177755.1)
  • Domains: Pfam-A via hmmscan --cut_ga — PurS (PF02700.20)
  • Sequence-level signal: ESM Atlas (EvolutionaryScale × BioHub) — exploratory
  • Controlled vocabulary: eggNOG-mapper 2.1.12 (Cantalapiedra et al. 2021, doi:10.1093/molbev/msab293), eggNOG 5.0 DB (Huerta-Cepas et al. 2019) — OG COG1828
  • Curated reference: UniProt I6Y8S6 (TrEMBL, unreviewed; Evidence at protein level)
  • Genome-wide structure: AlphaFold DB model (Jumper et al. 2021, doi:10.1038/s41586-021-03819-2; Varadi et al. 2024, doi:10.1093/nar/gkad1011) searched vs PDB with Foldseek (mean pLDDT 95.8)
  • Interaction network: STRING v12.0 (Szklarczyk et al. 2023, doi:10.1093/nar/gkac1000), taxon 83332, CC-BY 4.0 — 32 functional partner(s); context anchor purQ
  • Essentiality: genome-wide transposon mutagenesis in H37Rv — DeJesus et al. 2017 (mBio, doi:10.1128/mBio.02133-16, CC BY)
  • Proteomics: integrated mass-spectrometry abundance from PaxDb 5.0 (Huang et al. 2023, doi:10.1016/j.mcpro.2023.100640), taxon 83332 — weighted average of 16 datasets, incl. Schubert et al. 2013 (doi:10.1016/j.chom.2013.04.008) and Albrethsen et al. 2013 (doi:10.1074/mcp.M112.018846)
  • Functional category: TubercuList scheme (Cole et al. 1998, doi:10.1038/31159), via Mycobrowser (Kapopoulou et al. 2011, doi:10.1016/j.tube.2010.09.006)
  • Orthologues: reciprocal best hits (DIAMOND, Buchfink et al. 2021, doi:10.1038/s41592-021-01101-x) against Mycobrowser release 5 reference proteomes
  • Genomic context / operon: H37Rv annotation; operon predicted by co-directional intergenic distance (Salgado et al. 2000, doi:10.1073/pnas.030539397)
  • Transcriptional regulation: ISB signed TRN — TF ChIP-seq (Minch et al. 2015, doi:10.1038/ncomms6829) + TF overexpression (Rustad et al. 2014, doi:10.1186/gb-2014-15-11-502)
  • Physico-chemical properties: ExPASy ProtParam method via Biopython (Gasteiger et al. 2005), computed from the MTBC0 sequence
  • Primary literature: none located yet; annotation rests on the domain/homology sources above.

Ancestral MTBC0 protein sequence

>H37Rv|Rv0787A|
MARVVVHVMPKAEILDPQGQAIVGALGRLGHLGISDVRQGKRFELEVDDTVDDTTLAEIAESLLANTVIEDWTISRDPQ