Rv0601c Resolved · high auto-curated

H37Rv Rv0601c · MTBC0 - · 156 aa · 698524–698994 H37Rv (-) · RefSeq NP_215115.1

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Annotation: from legacy to revised

Legacy (H37Rv / Mycobrowser)two component sensor kinase HK2
MTBC0 PGAP re-annotation
Revised (this work)Two component sensor kinase HK2. Pfam: HAMP (PF00672.31).
Functional category (TubercuList)regulatory proteins

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) 3 publications

3 TB publications mention this gene. 3 publication(s) discuss this gene (3 in a M. tuberculosis context).

PublicationDate
Intra- and intermolecular domain interactions among novel two-component system proteins coded by Rv0600c, Rv0601c and Rv0602c of Mycobacterium tuberculosis. doi:10.1099/mic.0.019059-0 2009
Temperature and urea induced conformational changes of the histidine kinases from Mycobacterium tuberculosis. doi:10.1016/j.ijbiomac.2007.01.010 2007
Functional insights from the molecular modelling of a novel two-component system. doi:10.1016/j.bbrc.2006.04.019 2006

This layer CITES the literature and adds context; it does not change the verdict or the function stated elsewhere in this fiche. This distinguishes a gene that is dark because nobody has looked from one that is dark despite having been studied. Source: PubMed (whole): H37Rv locus tag + GENE NAME + ortholog identifiers (Mb…, MMAR_…, MSMEG_…, ML…, MAB_…), under a mycobacterial context filter; hits verified against the abstract text. Species-context counts distinguish M. tuberculosis literature from literature on other mycobacteria. phase76/phase77, 2026-07-13.

Intrinsic disorder (sequence + structure) partially disordered

Predicted disorder31% of residues (metapredict) · mean AlphaFold pLDDT 81.3
Disordered regions1 IDR(s), longest 34 aa [0-34]

carries a substantial disordered region (34/156 residues); disorder is a property, not a function

A property (biophysics), not a function. No LLPS/condensate claim is made from disorder alone. Verdict unchanged. Source: metapredict v3 (Emenecker/Holehouse) per-residue disorder + AlphaFold mean pLDDT (annotation_mtbc P16.13).

Conditional expression context (iModulons)

Member of 1 independently-modulated gene set(s): SG_9.

iModulon membership (independently-modulated gene sets from a 647-sample RNA-seq compendium): the conditional co-expression context. Co-expression is a regulatory context, NOT a molecular function. Source: iModulonDB / modulome_mtb (Yoo 2022).

Post-translational modifications

1 reported modified residue(s), incl. 1 phosphosite(s): Phosphohistidine; by autocatalysis @131.

Experimentally reported post-translational modification(s). A phosphosite indicates the protein is expressed and is a substrate of the M. tuberculosis Ser/Thr/Tyr kinase signalling network — a regulatory context, NOT a molecular function. Source: UniProt (Modified residue features; PTM sites curated from the M. tuberculosis literature).

CRISPRi vulnerability

Vulnerability index 0.62 (95% CI -0.57 to 2.42). 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 functionSensor part of a two component regulatory system.
Mycobrowser EC 2.7.13.3 · agrees with the atlas

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 Mb0617c · 100.0% identity
M. orygis RJtmp_000630 · 99.4% 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 O07777 SwissProt · reviewed · Evidence at protein level
UniProt nameSensor histidine kinase component HK2
EC (curated) EC 2.7.13.3
Curated functionMember of the three-protein two-component system HK1/HK2/TcrA. HK2 transfers its phosphoryl group to TcrA.

Functional vocabulary (eggNOG-mapper, orthology transfer)

COG category T Signal transduction mechanisms
Preferred nameyclK
eggNOG descriptionHistidine kinase
Orthologous groupCOG2972
EC number EC 2.7.13.3, EC 4.6.1.1
KEGG orthology K01768, K02484, K07653, K11617, K17292
KEGG pathways map00230, map02020, map02025, map04113, map04213
KEGG modules M00460, M00481, M00695, M00754
Gene Ontology (63) GO:0000155, GO:0000160, GO:0003674, GO:0003824, GO:0004672, GO:0004673, GO:0005488, GO:0005515, GO:0006464, GO:0006468, GO:0006793, GO:0006796 +51 more

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 0.0 · strong purifying
Polymorphic sites (≥ 0.1% of strains) 2 synonymous, 0 missense, 0 nonsense, 1 frameshift
Disruption 1 distinct premature-stop/frameshift site(s); most common in 0.10% of strains (150) · clonal

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) MTBC-specific

M. canettii dN/dS (deep-divergence selection) 0.39 (low power) · 2 consensus substitution(s)
low power (2 canettii-consensus substitution(s)); present in M. canettii but dN/dS not reliable
Genus-wide presence (~53 non-MTBC Mycobacterium) present in 0/53 (0%) · 0/4 closest MTBAP relatives
NOT MTBC-specific despite passing the strict presence filter: no hit at pident>=30 & qcov>=50 across the 53 non-MTBC genomes, BUT sub-threshold tblastn hit(s) exist (M_lentiflavum:57.5id/26cov;n=20;mtbap=0) — the gene is PRESENT BUT DIVERGENT in at least one non-MTBC Mycobacterium, not a genus-level innovation. Do not frame as MTBC-specific nor as a host-adaptation factor. Human non-homology, if needed, must be established directly (BLASTp vs human proteome), never inferred from this field.
Phylostratum (deepest detected homolog) MTBC-specific Mycobacterium Mycobacteriaceae Corynebacteriales Actinomycetia Bacteria

absent from the whole genus and from all outgroups tested — a candidate MTBC-specific innovation (confirm by synteny; rule out detection failure for short/divergent ORFs)

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) 4 in the ORF — 0 in the essential state, 0 growth-defect, 4 non-essential, 0 growth-advantage. Saturation 0.750, mean read count 80.6666666667. 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 4 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.

Proteomics (mass spectrometry) detected

MS detectiondetected in 2 of 16 independent MS datasets
Integrated abundance5.97 ppm · rank 2878/3519 (18.2th 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 (2 TM helixes)
DeepTMHMM classTM
TM helices (DeepTMHMM)2

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)

Length156 aa
Molecular weight16.6 kDa
Theoretical pI4.67
GRAVY0.244 (hydrophobic)
Aliphatic index115.3
Aromaticity0.026
Instability index25.5 (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
HAMPPF00672.31 8.8e-1261–116 HAMP domain

Genomic context (neighbours & predicted operon) operon of 2

Upstream (5' on genome)Rv0600c (- strand, 113 bp gap)
Downstream (3' on genome)tcrA (- strand, 43 bp gap)
Predicted operon Rv0601c · tcrA

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).

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: tcrA (two component DNA binding transcriptional regulator TcrA), high confidence from genomic context alone (score 967 excluding text-mining).

PartnerProductScoreNo text-miningChannels (≥400)
Rv0602c tcrA two component DNA binding transcriptional regulator TcrA 987 967 ctx neighborhood:700 cooccurence:616 coexpression:606 textmining:644
Rv0600c exp two component sensor kinase HK1 947 864 ctx neighborhood:511 experimental:500 textmining:630
Rv0981 mprA two-component response regulator MrpA 746 737 ctx cooccurence:404
Rv1033c trcR two component transcriptional regulator TrcR 784 730
Rv1248c kgd exp multifunctional 2-oxoglutarate dehydrogenase E1 component /2-oxoglutarate dehydrogenase dihydrolipoyllysine-residue succinyltransferase 758 729 experimental:422 database:538
Rv2496c bkdB exp 3-methyl-2-oxobutanoate dehydrogenase subunit beta 741 727 database:590
Rv2215 dlaT exp pyruvate dehydrogenase E2 component dihydrolipoamide acyltransferase 734 724 experimental:401 database:538
Rv0757 phoP two component system response transcriptional positive regulator PhoP 727 717
Rv2495c bkdC exp branched-chain keto acid dehydrogenase E2 component 724 713 experimental:401 database:538
Rv1734c hyp exp hypothetical protein 724 713 experimental:401 database:538
Rv1017c prsA exp ribose-phosphate pyrophosphokinase 712 696 database:586
Rv0648 alpha-mannosidase 691 692 coexpression:692
Rv3765c tcrX two component transcriptional regulator TcrX 752 689
Rv0903c prrA two component transcriptional regulator PrrA 739 689
Rv0603 hyp hypothetical protein 675 675 ctx neighborhood: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

  • Annotation from H37Rv (no MTBC0 1:1 anchor; H37Rv protein used): two component sensor kinase HK2
  • Pfam (hmmscan --cut_ga): HAMP PF00672.31 (E=9e-12)
  • (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_215115.1)
  • Domains: Pfam-A via hmmscan --cut_ga — HAMP (PF00672.31)
  • 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 COG2972
  • Curated reference: UniProt O07777 (SwissProt, reviewed; 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 81.3)
  • Interaction network: STRING v12.0 (Szklarczyk et al. 2023, doi:10.1093/nar/gkac1000), taxon 83332, CC-BY 4.0 — 61 functional partner(s); context anchor tcrA
  • 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)
  • 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

>H37Rv|Rv0601c|
MALVLAAAGAVTVVQFRDAAHEADPDGALRGLTDDITADLVRELVTILPIVLVIAAVAAYLLSRAALRPVDRIRAAAQTLTTTPHPDTDAPLPVPPTDDEIAWLATTLNTMLTRLQRALAHEQQFVADASHELRTPLALLTTELELRCAGPDPPTS