Q9KZ33

UniProt ID: Q9KZ33
Organism: Streptomyces coelicolor (strain ATCC BAA-471 / A3(2) / M145)
Review Status: COMPLETE
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Gene Description

SCO7099 (Q9KZ33) is a predicted extracytoplasmic function (ECF) sigma factor in Streptomyces coelicolor A3(2). It contains ECF Sigma-70, RNA polymerase sigma r3/r4-like, and winged helix-like DNA-binding domains, consistent with the minimal two-domain architecture (sigma2 and sigma4) characteristic of ECF sigma factors. As a sigma factor, it is expected to associate with the RNA polymerase core enzyme and direct transcription initiation at a specific but currently unknown set of promoters, likely in response to extracytoplasmic signals. S. coelicolor encodes 64-65 sigma factors, the majority belonging to the ECF family. SCO7099 remains functionally uncharacterized: no regulon, promoter specificity, inducing signal, anti-sigma factor partner, or knockout phenotype has been determined. A 2024 systematic overexpression study failed to recover transformants for SCO7099, suggesting potential toxicity from uncontrolled expression, but no follow-up experiments resolved this observation.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0016987 sigma factor activity
IBA
GO_REF:0000033 		ACCEPT
Summary: Sigma factor activity is well-supported by domain architecture. Q9KZ33 contains the ECF_Sigma-70_Domain (IPR052704), RNA_pol_sigma_r3/r4-like (IPR013324), and WH-like_DNA-bd_sf (IPR036388) domains, which constitute the minimal sigma2 and sigma4 domain architecture required for promoter recognition and RNA polymerase interaction. The IBA evidence is based on PANTHER phylogenetic inference (PTN001249270) with L0TCG5 (SigJ from Mycobacterium tuberculosis) as the with/from reference, a genuine ECF sigma factor ortholog in actinobacteria.
Reason: The domain architecture unambiguously supports classification as an ECF sigma factor. The PANTHER phylogenetic inference is well-grounded, with a bona fide ECF sigma factor ortholog as the reference. Although no direct experimental evidence exists for Q9KZ33 itself, the structural and phylogenetic evidence for sigma factor activity is strong.
Supporting Evidence:
file:STRCO/Q9KZ33/Q9KZ33-deep-research-falcon.md
The presence of ECF_Sigma-70_Domain and RNA_pol_sigma_r3/r4-like domains strongly supports classification as a bona fide sigma factor capable of directing transcription initiation
GO:2000142 regulation of DNA-templated transcription initiation
IEA
GO_REF:0000108 		ACCEPT
Summary: This annotation is a correct logical inference from the sigma factor activity (GO:0016987) annotation via GO_REF:0000108 (inter-ontology logical links). Sigma factors by definition modulate transcription initiation by directing RNA polymerase to specific promoters, so involvement in regulation of DNA-templated transcription initiation follows directly from the molecular function annotation.
Reason: This BP annotation is automatically derived from the MF sigma factor activity annotation using inter-ontology inference rules. Since sigma factors regulate which promoters RNA polymerase recognizes, they inherently regulate transcription initiation. The inference is biologically sound.
Supporting Evidence:
file:STRCO/Q9KZ33/Q9KZ33-deep-research-falcon.md
sigma factors serve as dissociable regulatory subunits of bacterial RNA polymerase...the sigma factor binds specifically to promoter elements

Core Functions

SCO7099 is a predicted ECF sigma factor that associates with RNA polymerase core enzyme to direct transcription initiation at specific promoters. Its regulon, promoter specificity, and inducing signal remain unknown.

Molecular Function:
sigma factor activity
Directly Involved In:
regulation of DNA-templated transcription initiation
Cellular Locations:
cytoplasm
Supporting Evidence:
  • file:STRCO/Q9KZ33/Q9KZ33-deep-research-falcon.md
    sigma factors serve as dissociable regulatory subunits of bacterial RNA polymerase...the sigma factor binds specifically to promoter elements

References

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Suggested Questions for Experts

Q: What is the regulon of SCO7099 and under what conditions is it active?

Q: Does SCO7099 have a cognate anti-sigma factor encoded in its genomic neighborhood?

Q: Is the failure to recover overexpression transformants due to toxicity from transcriptional dysregulation, or a technical artifact?

Suggested Experiments

Experiment: Construct a clean deletion mutant of SCO7099 and assess phenotypes under diverse stress conditions, developmental stages, and nutrient limitations.

Hypothesis: SCO7099 deletion may reveal condition-specific phenotypes related to extracytoplasmic stress response.

Experiment: Use an inducible promoter system (e.g., tipA-thiostrepton) to express SCO7099 at controlled levels and profile transcriptome changes by RNA-seq.

Hypothesis: Controlled expression will identify the SCO7099 regulon without the toxicity observed during constitutive overexpression.

Experiment: ChIP-seq with epitope-tagged SCO7099 expressed from its native locus to map genome-wide DNA-binding sites.

Hypothesis: SCO7099 binds a specific set of promoters with a characteristic ECF sigma factor -35/-10 motif.

External Prediction Reviews

These computational predictions are reviewed separately from the GOA annotation set used for this review. The assessments below are from this project and do not constitute official GO annotations or endorsement by GO/UniProt. They are not included in the existing annotation review above.

ProtNLM2 External predictions

View prediction review YAML · Q9KZ33-protnlm-predictions-review.yaml · Review status: COMPLETE

The ECF sigma-factor architecture supports a role in transcription initiation, adding a process annotation to the existing sigma-factor activity.

Source documents: genes/STRCO/Q9KZ33/Q9KZ33-uniprot.txt · genes/STRCO/Q9KZ33/Q9KZ33-goa.tsv

Review score: 2 = concordant with evidence; 1 = uncertain; 0 = discordant with evidence. This is an assessment score, not a model probability.

GO:0006352 DNA-templated transcription initiation GO_BP
COR — Correct novel prediction Review score: 2/2
Prediction method: ProtNLM2 · Version: UniProt 2024_06 pilot
Review rationale: The target has ECF sigma-70 domain assignments and a curated IBA for sigma factor activity. A sigma factor participates in promoter recognition and initiation by bacterial RNA polymerase, supporting the predicted biological process. The cached annotation regulation of DNA-templated transcription initiation is related but is not a more specific subtype of initiation itself. The exact initiation term is absent from the cached annotations; this is a supported process inference from the established molecular function.
Supporting Evidence:
  • file:STRCO/Q9KZ33/Q9KZ33-uniprot.txt: "ID Q9KZ33_STRCO Unreviewed; 300 AA. ... DR GO; GO:0016987; F:sigma factor activity; IBA:GO_Central. ... DR InterPro; IPR052704; ECF_Sigma-70_Domain. ... DR PANTHER; PTHR30173:SF43; ECF RNA POLYMERASE SIGMA FACTOR SIGI-RELATED; 1."

Deep Research

Falcon

(Q9KZ33-deep-research-falcon.md)

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