Rv1139c Family assigned · medium auto-curated

H37Rv Rv1139c · MTBC0 mtbc0_001224 · 166 aa · 1274925–1275425 MTBC0 (-) · RefSeq NP_215655.1

Genomic neighbourhood (genome browser)

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Annotation: from legacy to revised

Legacy (H37Rv / Mycobrowser)hypothetical protein
MTBC0 PGAP re-annotationisoprenylcysteine carboxyl methyltransferase family protein
Revised (this work)Isoprenylcysteine carboxyl methyltransferase family protein. Pfam: ICMT (PF04140.20), PEMT (PF04191.19).
Functional category (TubercuList)cell wall and cell processes

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

In the literature (TB corpus sweep) 2 publications

Found under: H37Rv (2).

2 TB publications mention this gene. 2 publication(s) mention this gene (title/abstract), verified against the text. The atlas states the function; these are the primary sources that discuss it.

PublicationDate
Analysis of differentially expressed proteins in late-stationary growth phase of Mycobacterium tuberculosis H37Rv. doi:10.1002/bab.1137 2014
The Mycobacterium tuberculosis extracytoplasmic-function sigma factor SigL regulates polyketide synthases and secreted or membrane proteins and is required for virulence. doi:10.1128/JB.187.20.7062-7071.2005 2005

This layer CITES the literature, it does not change the verdict or the function. A gene may be heavily studied (as an antigen, a resistance determinant, a drug target) while its molecular function is settled elsewhere in the fiche. 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 · 1 % of gene

NeighboursrsC (Rv1138c, - strand)
Overlap4 bp, 1 % 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 1.29 (95% CI -0.33 to 3.90). 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)

Mycobrowser functionFunction unknown

The legacy Mycobrowser record is shown for verification. Mycobrowser is no longer maintained; its EC numbers predate recent nomenclature revisions, so a class change usually reflects re-numbering, not a conflict.

Orthologues (reciprocal best hits across mycobacteria)

M. bovis Mb1171c · 100.0% identity
M. marinum MMAR_4314 · 84.1% identity
M. smegmatis MSMEG_0809 · 64.8% identity
M. orygis RJtmp_001201 · 100.0% 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 O06539 TrEMBL · unreviewed · Evidence at protein level
UniProt nameConserved hypothetical membrane protein

Functional vocabulary (eggNOG-mapper, orthology transfer)

COG category S Function unknown
eggNOG descriptionIsoprenylcysteine carboxyl methyltransferase
Orthologous groupCOG1755
KEGG orthology K16168

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.

Conservation & selection (intra-MTBC, 145 209 strains)

pN/pS n/a
Polymorphic sites (≥ 0.1% of strains) 0 synonymous, 4 missense, 0 nonsense, 0 frameshift

pN/pS from segregating SNPs (singletons removed) normalised by possible sites. Low pN/pS = purifying selection (a strong signal that a "hypothetical" is a real, constrained gene). A high pN/pS is ambiguous: relaxed constraint or positive selection (drug resistance, antigenic variation) inflate it; e.g. rpoB/katG/pncA score high here for resistance, not loss of function. A clonal disruption (one allele over a clade) suggests lineage pseudogenisation; a convergent one (many independent alleles) is typical of resistance loss-of-function.

Outgroup conservation (beyond the MTBC) Bacteria

M. canettii dN/dS (deep-divergence selection) inf (low power) · 1 consensus substitution(s)
low power (1 canettii-consensus substitution(s)); present in M. canettii but dN/dS not reliable
Genus-wide presence (~53 non-MTBC Mycobacterium) present in 50/53 (94%) · mean identity 80.6% · 4/4 closest MTBAP relatives
conserved across the genus (present in 50/53 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 2/13 non-Mycobacterium reference genomes (down to Bacteria) · mean identity 50.7%
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)

DeJesus 2017 callNE · non-essential
What the call meansnon-essential
TA sites (Himar1) 13 in the ORF — 0 in the essential state, 0 growth-defect, 13 non-essential, 0 growth-advantage. Saturation 1.000, mean read count 135.307692308. A region of the protein devoid of TA sites is invisible to this assay: nothing can be inferred about it, in either direction.

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.

Proteomics (mass spectrometry) detected

MS detectiondetected in 6 of 16 independent MS datasets
Integrated abundance3.62 ppm · rank 3046/3519 (13.5th 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.

Predicted localisation (DeepTMHMM + lipobox)

Predictionpredicted membrane protein (5 TM helixes)
DeepTMHMM classTM
TM helices (DeepTMHMM)5

Transmembrane topology and signal peptide from DeepTMHMM (deep-learning reference predictor); lipoproteins from a (myco)bacterial lipobox motif. A sequence-based prediction of subcellular context.

Physico-chemical properties (computed, ProtParam)

Length166 aa
Molecular weight19.0 kDa
Theoretical pI10.67
GRAVY0.556 (hydrophobic)
Aliphatic index122.7
Aromaticity0.127
Instability index45.2 (unstable)

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
ICMTPF04140.20 1.0e-2673–163 Isoprenylcysteine carboxyl methyltransferase (ICMT) family
PEMTPF04191.19 8.8e-0875–163 Phospholipid methyltransferase

Structural search (AlphaFold DB model, Foldseek vs PDB — genome-wide) pLDDT 92.1

PDB hitprobTM-scoreE-valueDescription
4a2n-assembly1_B 1.00 0.70 1.3e-03 sig 4a2n-assembly1_B Crystal Structure of Ma-ICMT
5v7p-assembly1_A 1.00 0.72 1.6e-03 sig 5v7p-assembly1_A Atomic structure of the eukaryotic intramembrane Ras methyltransferase ICMT (isoprenylcysteine carboxyl methyltransferase), in complex with a monobody
5vg9-assembly1_A 1.00 0.72 3.5e-03 sig 5vg9-assembly1_A Structure of the eukaryotic intramembrane Ras methyltransferase ICMT (isoprenylcysteine carboxyl methyltransferase) without a monobody

Foldseek search of the AlphaFold DB model (mean pLDDT 92.1, 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)Rv1138c (- strand, -4 bp gap)
Downstream (3' on genome)Rv1140 (+ strand, 361 bp gap)
Predicted operon Rv1138c · Rv1139c

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 (2 TF) Rv1404 (represses) · Rv2034 (represses)

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: Rv1138c (oxidoreductase), high confidence from genomic context alone (score 979 excluding text-mining). This association is the citable seed of a function hypothesis for this hypothetical protein.

PartnerProductScoreNo text-miningChannels (≥400)
Rv1138c oxidoreductase 988 979 ctx neighborhood:881 cooccurence:767 textmining:489
Rv1660 pks10 chalcone synthase 926 901 ctx cooccurence:774 coexpression:532
Rv1665 pks11 chalcone synthase 904 871 ctx cooccurence:774
Rv1372 pks18 alpha-pyrone synthesis polyketide synthase-like protein 875 832 ctx cooccurence:702 coexpression:400
Rv1137c Hypothetical protein; Rv1137c, (MTCI65.04c), len: 122 aa. Hypothetical unknown protein. 767 767 ctx neighborhood:737
Rv2638 hyp hypothetical protein 606 215 textmining:519
Rv2161c hyp hypothetical protein 805 55 textmining:803
Rv2781c oxidoreductase 815 54 textmining:813
Rv0952 sucD succinyl-CoA ligase subunit alpha 437 50 textmining:432
Rv3224 iron-regulated short-chain dehydrogenase/reductase 657 47 textmining:655
Rv3572 hyp hypothetical protein 656 47 textmining:654
Rv2192c trpD anthranilate phosphoribosyltransferase 523 47 textmining:520
Rv2643 arsC arsenic-transport integral membrane protein ArsC 480 46 textmining:478
Rv3089 fadD13 long chain-fatty-acid--CoA ligase FadD13 431 44 textmining:430
Rv0820 phoT phosphate ABC transporter ATP-binding protein PhoT 514 42 textmining:514

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

  • Legacy H37Rv annotation: hypothetical protein
  • MTBC0 PGAP product: isoprenylcysteine carboxyl methyltransferase family protein
  • Pfam (hmmscan --cut_ga): ICMT PF04140.20 (E=1e-26), PEMT PF04191.19 (E=9e-08)
  • (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 NP_215655.1)
  • Domains: Pfam-A via hmmscan --cut_ga — ICMT (PF04140.20), PEMT (PF04191.19)
  • 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 COG1755
  • Curated reference: UniProt O06539 (TrEMBL, unreviewed; Evidence at protein level)
  • Intra-MTBC selection: pN/pS and disruption from SPDI variants of 145 209 MTBC strains (this work, local collection vs H37Rv NC_000962.3)
  • 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 92.1)
  • Interaction network: STRING v12.0 (Szklarczyk et al. 2023, doi:10.1093/nar/gkac1000), taxon 83332, CC-BY 4.0 — 18 functional partner(s); context anchor Rv1138c
  • 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
  • Predicted localisation: DeepTMHMM (Hallgren et al. 2022, doi:10.1101/2022.04.08.487609) for transmembrane topology and signal peptide
  • Primary literature: none located yet; annotation rests on the domain/homology sources above.

Ancestral MTBC0 protein sequence

>mtbc0_001224|Rv1139c|
MYYLLILAVVFERLAELVVAQRNARWSFAQGGKEFGRPHYVVMVILHTALLLGCVVEPWALHRPFIPWLGWPMLAVVVASQGLRWWCVKSLGKRWNTRVIVLPHATLVRRGPYRWMRHPNYVAVVAEGFALPLVHTAWLTALVFTLANATLLTVRLRVENSVLGYI