Rv0600c Resolved · high auto-curated

H37Rv Rv0600c · MTBC0 - · 168 aa · 697904–698410 H37Rv (-) · RefSeq NP_215114.2

Genomic neighbourhood (genome browser)

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Annotation: from legacy to revised

Legacy (H37Rv / Mycobrowser)two component sensor kinase HK1
MTBC0 PGAP re-annotation
Revised (this work)Two component sensor kinase HK1. Pfam: HATPase_c (PF02518.32).
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 disorder18% of residues (metapredict) · mean AlphaFold pLDDT 84.6
Disordered regions1 IDR(s), longest 31 aa [137-168]

carries a substantial disordered region (31/168 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).

CRISPRi vulnerability

Vulnerability index 1.26 (95% CI -1.11 to 4.98). 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 Mb0616c · 99.4% identity
M. orygis RJtmp_000629 · 98.8% 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 O07778 SwissProt · reviewed · Evidence at protein level
UniProt nameSensor histidine kinase component HK1
EC (curated) EC 2.7.13.3
Curated functionMember of the three-protein two-component system HK1/HK2/TcrA. Kinase that binds ATP and catalyzes the transfer of a phosphoryl group from ATP to HK2.

Functional vocabulary (eggNOG-mapper, orthology transfer)

COG category T Signal transduction mechanisms
eggNOG descriptionHistidine kinase
Orthologous groupCOG0642

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 0.36 · purifying
Polymorphic sites (≥ 0.1% of strains) 1 synonymous, 1 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) 0.507 · 17 consensus substitution(s)
elevated dN/dS vs M. canettii (0.507) — relaxed or positive selection at deep divergence
Genus-wide presence (~53 non-MTBC Mycobacterium) present in 45/53 (85%) · mean identity 35.8% · 2/4 closest MTBAP relatives
conserved across the genus (present in 45/53 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 11/13 non-Mycobacterium reference genomes (down to Bacteria) · mean identity 36.7%
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) 4 in the ORF — 0 in the essential state, 0 growth-defect, 4 non-essential, 0 growth-advantage. Saturation 1.000, mean read count 139.25. 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) not detected

Not detected in the mass-spectrometry datasets integrated by PaxDb. This is not evidence of absence: low-abundance, condition-specific, or MS-refractory proteins (e.g. small, highly hydrophobic, or repetitive PE/PPE families with few tryptic peptides) are systematically under-sampled.

Physico-chemical properties (computed, ProtParam)

Length168 aa
Molecular weight17.9 kDa
Theoretical pI5.55
GRAVY-0.363 (hydrophilic)
Aliphatic index79.7
Aromaticity0.042
Instability index20.1 (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
HATPase_cPF02518.32 6.7e-2534–140 Histidine kinase-, DNA gyrase B-, and HSP90-like ATPase

Structural search (AlphaFold DB model, Foldseek vs PDB — genome-wide) pLDDT 84.6

PDB hitprobTM-scoreE-valueDescription
5c93-assembly1_B 1.00 0.83 2.0e-12 sig 5c93-assembly1_B Histidine kinase with ATP
3sl2-assembly1_A 1.00 0.84 3.6e-12 sig 3sl2-assembly1_A ATP Forms a Stable Complex with the Essential Histidine Kinase WalK (YycG) Domain
9eut-assembly1_B 1.00 0.85 5.2e-12 sig 9eut-assembly1_B Cryo-EM structure of the full-length Pseudomonas aeruginosa bacteriophytochrome in its Pr state
4biz-assembly3_A 1.00 0.88 7.5e-12 sig 4biz-assembly3_A Crystal structure of CpxAHDC (orthorhombic form 2)
4biz-assembly2_C 1.00 0.83 2.8e-12 sig 4biz-assembly2_C Crystal structure of CpxAHDC (orthorhombic form 2)

Foldseek search of the AlphaFold DB model (mean pLDDT 84.6, 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)

Upstream (5' on genome)vapB27 (- strand, 103 bp gap)
Downstream (3' on genome)Rv0601c (- strand, 113 bp gap)

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) Rv0302 (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: tcrA (two component DNA binding transcriptional regulator TcrA), high confidence from genomic context alone (score 938 excluding text-mining).

PartnerProductScoreNo text-miningChannels (≥400)
Rv0602c tcrA two component DNA binding transcriptional regulator TcrA 970 938 ctx neighborhood:441 cooccurence:762 textmining:541
Rv0903c prrA two component transcriptional regulator PrrA 914 897 ctx cooccurence:766
Rv3246c mtrA two component DNA-binding response regulator MtrA 912 897 ctx cooccurence:767
Rv0491 regX3 two component sensory transduction protein RegX 900 896 ctx cooccurence:765
Rv0981 mprA two-component response regulator MrpA 896 892 ctx cooccurence:756
Rv1033c trcR two component transcriptional regulator TrcR 913 891 ctx cooccurence:755
Rv0757 phoP two component system response transcriptional positive regulator PhoP 895 891 ctx cooccurence:753
Rv3765c tcrX two component transcriptional regulator TcrX 911 887 ctx cooccurence:746
Rv2884 transcriptional regulator 877 872 ctx cooccurence:710
Rv1027c kdpE transcriptional regulator KdpE 892 871 ctx cooccurence:707
Rv0601c exp two component sensor kinase HK2 947 864 ctx neighborhood:511 experimental:500 textmining:630
Rv0818 transcriptional regulator 809 801 ctx cooccurence:548
Rv1248c kgd exp multifunctional 2-oxoglutarate dehydrogenase E1 component /2-oxoglutarate dehydrogenase dihydrolipoyllysine-residue succinyltransferase 758 728 experimental:422 database:538
Rv2496c bkdB exp 3-methyl-2-oxobutanoate dehydrogenase subunit beta 742 728 database:590
Rv1734c hyp exp hypothetical protein 727 716 experimental:401 database:538

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 HK1
  • Pfam (hmmscan --cut_ga): HATPase_c PF02518.32 (E=7e-25)
  • (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_215114.2)
  • Domains: Pfam-A via hmmscan --cut_ga — HATPase_c (PF02518.32)
  • 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 COG0642
  • Curated reference: UniProt O07778 (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 84.6)
  • 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)
  • 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|Rv0600c|
MPITPLLHESVARFAATGADITTRAEPDLFVSIDPDHLRRILTAVLDNAITHGDGEIAVTAHARDGAVDIGVRDHGPGFADHFLPVAFDRFTRADTARGGRGSGLGLAIVAALTTTHGGHANATNHPDGGAELRITLPTPRPPFHEELPRITSSDTKDPNREHDTSDQ