rpoH

Gene Description

RpoH (sigma-32) is the heat-shock sigma factor of Pseudomonas putida, a member of the sigma-70 (RpoD) family of RNA polymerase sigma factors. As a dissociable specificity subunit of RNA polymerase, it binds the core enzyme to form an alternative holoenzyme that directs transcription initiation from a distinct class of heat-shock promoters. Through region 2 it contacts core RNAP and recognizes the -10 promoter element and promotes DNA melting, and through its C-terminal region 4 helix-turn-helix motif it recognizes the -35 element. RpoH activates the regulon encoding molecular chaperones and ATP-dependent proteases (e.g. DnaK/DnaJ/GrpE, GroEL/GroES, HtpG, ClpB, Lon, FtsH, IbpA) that refold or degrade damaged proteins, thereby maintaining protein homeostasis under heat and other proteotoxic stresses (including aromatic solvent exposure and elevated pressure). Its activity and stability are themselves controlled by a chaperone- and protease-mediated negative feedback circuit. RpoH acts in the cytoplasm as part of the RNA polymerase holoenzyme on the bacterial chromosome.

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0003677 DNA binding	IEA GO_REF:0000104	KEEP AS NON CORE	Summary: RpoH binds promoter DNA (recognizing -10 and -35 elements) as part of the RNA polymerase holoenzyme; DNA binding is a genuine activity but is a general parent of the more informative sigma factor activity term. Reason: Sigma factors do bind DNA sequence-specifically via region 2 (-10) and region 4 (-35, HTH motif), so the annotation is not wrong. However, it is a generic supporting molecular function; the core, more informative MF for this gene is GO:0016987 sigma factor activity. Retain as non-core.
GO:0003700 DNA-binding transcription factor activity	IEA GO_REF:0000002	REMOVE	Summary: This InterPro2GO mapping assigns the general transcription factor activity term. By GO convention, bacterial sigma factors are NOT classified as DNA-binding transcription factors; they are basal/general transcription machinery and should receive GO:0016987 sigma factor activity instead. Reason: GO has an explicit convention that sigma factors are not DNA-binding transcription factors (GO:0003700) but rather are captured by GO:0016987 sigma factor activity, which is already annotated here. GO:0003700 is the wrong molecular function class for a sigma factor and is redundant/misleading. The correct MF term is present.
GO:0005737 cytoplasm	IEA GO_REF:0000120	ACCEPT	Summary: RpoH acts in the cytoplasm as part of the RNA polymerase holoenzyme on the nucleoid; cytoplasmic localization is consistent with UniProt subcellular location and with its role as a soluble, non-secreted transcription factor. Reason: Consistent with UniProt SUBCELLULAR LOCATION (Cytoplasm) and the known biology of sigma factors acting on the chromosome within the cytoplasm/nucleoid.
GO:0006352 DNA-templated transcription initiation	IEA GO_REF:0000120	ACCEPT	Summary: The primary biological role of RpoH is to promote sequence-specific transcription initiation by RNA polymerase at heat-shock promoters. This is a core process term for the gene. Reason: Directly captures the central function of a sigma factor as an initiation factor (UniProt FUNCTION states sigma factors promote attachment of RNAP to initiation sites). Core biological process.
GO:0006355 regulation of DNA-templated transcription	IEA GO_REF:0000002	KEEP AS NON CORE	Summary: As an alternative sigma factor, RpoH regulates transcription of the heat-shock regulon. The term is correct but general relative to the more specific initiation terms. Reason: Correct and consistent with sigma factor biology, but a broad regulatory term. The more specific GO:0006352 (transcription initiation) and GO:2000142 (regulation of transcription initiation) better capture the precise role; retain as non-core context.
GO:0009408 response to heat	IEA GO_REF:0000104	ACCEPT	Summary: RpoH (sigma-32) is the master regulator of the heat-shock response, induced after heat upshift and driving chaperone/protease expression. Response to heat is a well-supported core biological process for this gene. Reason: Strongly supported by the canonical biology of sigma-32 and by P. putida-specific data showing rapid induction of RpoH-dependent heat-shock genes after temperature upshift (Ito et al. 2014). Core process. Supporting Evidence: file:PSEPK/rpoH/rpoH-deep-research-falcon.md In Pseudomonas putida the heat-shock response is controlled by sigma-32 (encoded by rpoH); heat-shock gene expression increases within ~10 min of temperature upshift and correlates with sigma-32 levels, and rpoH (PP_5108) is upregulated under proteotoxic stresses such as elevated pressure and aromatic solvent exposure.
GO:0010468 regulation of gene expression	IEA GO_REF:0000104	KEEP AS NON CORE	Summary: A very general regulatory term; correct in essence but far less informative than the specific transcription-initiation regulation terms already annotated. Reason: Not incorrect, but high-level and subsumed by the more specific transcription regulation/initiation terms. Retain as non-core rather than core.
GO:0016987 sigma factor activity	IEA GO_REF:0000120	ACCEPT	Summary: This is the correct, specific molecular function for RpoH. It binds RNA polymerase core enzyme and confers heat-shock promoter specificity. This is the core molecular function of the gene. Reason: Precisely matches the gene product's identity as a sigma-70 family RpoH sigma factor (UniProt, HAMAP MF_00961, TIGR02392). This is the preferred MF term for sigma factors per GO convention.
GO:2000142 regulation of DNA-templated transcription initiation	IEA GO_REF:0000108	ACCEPT	Summary: RpoH regulates which genes RNA polymerase initiates transcription at, so regulation of transcription initiation accurately captures its role. Inferred from the sigma factor activity annotation. Reason: Logically consistent with sigma factor activity (the GOC inference is from GO:0016987) and biologically accurate for a promoter-selectivity factor.

Gene Description

Existing Annotations Review

Core Functions

Acts as the heat-shock (sigma-32) specificity subunit of RNA polymerase, binding the core enzyme and directing sequence-specific transcription initiation at heat-shock promoters to activate the chaperone/protease regulon that maintains protein homeostasis under stress.

References

Deep Research

Falcon

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