MTBC Gene Atlas

ncRv11846 / MrsI MTB000142

ncRNA Putative small regulatory RNA

This is an RNA, not a coding gene: it belongs to a separate track and carries none of the protein evidence layers.

Location

2096766–2096867 (+ strand), 102 nt, on H37Rv (NC_000962.3). Intergenic (no overlapping coding sequence). Upstream neighbour Rv1846c (167 bp). Downstream neighbour Rv1847 (10 bp).

Intra-MTBC variation

Genomes surveyed145,209
Variable sites81
Variants reaching 0.1 % of genomes 0
Carriers of the most widespread variant60

Coverage control

Variant density inside this RNA: 79.4 sites/100 bp, versus 76.3 in the flanking ±500 bp (GC 70.6 %). The flanks act as an internal witness: if variants are called normally around the RNA but none becomes widespread inside it, the constraint is real rather than a sequencing gap.

Verdict: COUVERTURE OK -> invariance biologique plausible

Read with care: constraint is not function. This RNA mutates like its surroundings, but no variant spreads through the population — which is evidence of selection acting on it, not evidence of what it does. Secondary-structure pairing was tested across the RNA set and did not explain this constraint.

Predicted secondary structure

62.7 % of bases are paired in the minimum-free-energy fold (64 paired, 38 unpaired). Folded in isolation; the in vivo structure may differ (partners, co-transcriptional folding).

Literature characterised

Renamed MrsI (mycobacterial regulatory sRNA in iron) by Gerrick et al. (2018), who characterised its regulon and showed direct binding to bfrA: MrsI drives an ANTICIPATORY iron-sparing response, induced ahead of iron limitation under several stresses.

Read with care. The regulon and the bfrA interaction are established in the cited work; this atlas adds only the intra-MTBC invariance, which is consistent with a functional RNA but does not by itself demonstrate anything.

Why we nearly missed it. Invisible to any search by identifier: the paper renames the RNA, so 'ncRv11846' appears once and 'MrsI' everywhere after. Same failure mode as Rv1363c/OmamC (P8.5) — an object renamed by its authors disappears from identifier-based sweeps.

Sweep: tbmonitor TB corpus (~330k PubMed abstracts), name sweep of 2026-08-10; positive controls MTS2823 (6 papers), mcr11 (3), Mcr7 (2) all returned hits, so a zero here is a measured absence and not a broken query.

Legacy record

Supported by sRNA-Seq in H37Rv (see DeJesus et al. 2017)

Sources

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