sap Resolved · high auto-curated
H37Rv Rv3821 · MTBC0 mtbc0_004050 ·
237 aa · 4310083–4310796 (+) ·
RefSeq NP_218338.1
Annotation: from legacy to revised
| Legacy (H37Rv / Mycobrowser) | integral membrane protein |
|---|---|
| MTBC0 PGAP re-annotation | sulfolipid-1 biosynthesis transporter Sap |
| Revised (this work) | Sulfolipid-1 biosynthesis transporter Sap. Pfam: SfLAP (PF11139.15). |
Auto-curated: this verdict and function were generated by rules from PGAP + Pfam + Foldseek and have not been hand-reviewed.
Curated reference (UniProt)
| UniProt |
O07802
SwissProt · reviewed
· Evidence at protein level
|
|---|---|
| UniProt name | Sulfolipid-1 exporter Sap |
| Curated function | Required for the transport across the inner membrane of sulfolipid-1 (SL-1), which is a major cell wall lipid of pathogenic mycobacteria. Could also transport SL1278 (2-palmitoyl-3-(C43)-phthioceranyl-alpha, alpha'-D-trehalose-2'-sulfate), which is the precursor of SL-1. May potentiate SL-1 levels and confer specificity for sulfolipids over structurally similar glycolipids. |
Functional vocabulary (eggNOG-mapper, orthology transfer)
| COG category |
S Function unknown
|
|---|---|
| eggNOG description | Sap, sulfolipid-1-addressing protein |
| Orthologous group | 2F6DN |
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 | 1.356 · diversifying/relaxed |
|---|---|
| Polymorphic sites (≥ 0.1% of strains) | 2 synonymous, 7 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.
Domains (Pfam, hmmscan --cut_ga)
| Pfam | Accession | i-Evalue | Residues | Description |
|---|---|---|---|---|
SfLAP | PF11139.15 | 4.0e-57 | 5–235 | Sap, sulfolipid-1-addressing protein |
Functional interaction network (STRING v12, guilt-by-association)
Closest characterised functional partner: papA2 (trehalose-2-sulfate acyltransferase), medium confidence from genomic context alone (score 549 excluding text-mining).
| Partner | Product | Score | No text-mining | Channels (≥400) |
|---|---|---|---|---|
Rv3822 chp1 hyp |
hypothetical protein | 850 | 707 ctx | neighborhood:703 textmining:511 |
Rv3820c papA2 |
trehalose-2-sulfate acyltransferase | 681 | 549 ctx | neighborhood:542 |
Rv1337 |
integral membrane protein | 517 | 55 | textmining:510 |
Rv0227c |
membrane protein | 440 | 55 | textmining:432 |
Rv0295c stf0 hyp |
hypothetical protein | 549 | 53 | textmining:544 |
Rv1275 lprC |
lipoprotein LprC | 442 | 51 | textmining:437 |
Rv2169c |
transmembrane protein | 518 | 50 | textmining:514 |
Rv1799 lppT |
lipoprotein LppT | 440 | 50 | textmining:435 |
Rv3823c mmpL8 |
integral membrane transport protein MmpL8 | 406 | 47 | textmining:403 |
Rv0625c |
transmembrane protein | 548 | 46 | textmining:546 |
Rv3271c |
integral membrane protein | 547 | 44 | textmining:546 |
Rv3064c |
integral membrane protein | 544 | 44 | textmining:543 |
Rv0585c |
integral membrane protein | 653 | 41 | textmining:653 |
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 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: integral membrane protein
- MTBC0 PGAP product: sulfolipid-1 biosynthesis transporter Sap
- Pfam (hmmscan --cut_ga): SfLAP PF11139.15 (E=4e-57)
- (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_218338.1)
- Domains: Pfam-A via hmmscan --cut_ga — SfLAP (PF11139.15)
- 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
2F6DN - Curated reference: UniProt O07802 (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)
- Interaction network: STRING v12.0 (Szklarczyk et al. 2023,
doi:10.1093/nar/gkac1000), taxon 83332, CC-BY 4.0 —
13 functional partner(s); context anchor
papA2 - Primary literature: none located yet; annotation rests on the domain/homology sources above.
Ancestral MTBC0 protein sequence
>mtbc0_004050|Rv3821|sap MWSTVLVLALSVICEPVRIGLVVLMLNRRRPLLHLLTFLCGGYTMAGGVAMVTLVVLGATPLAGHFSVAEVQIGTGLIALLIAFALTTNVIGKHVRRATHARVGDDGGRVLRESVPPSGAHKLAVRARCFLQGDSLYVAGVSGLGAALPSANYMGAMAAILASGATPATQALAVVTFNVVAFTVAEVPLVSYLAAPRKTRAFMAALQSWLRSRSRRDAALLVAAGGCLMLTLGLSNL