psrA (PA3006) review notes

Locus PA3006, UniProt Q9HZJ9 (unreviewed, PE 1; crystal structure PDB 2FBQ from
structural genomics), 233 aa. TetR-family regulator: TetR_N HTH (PF00440, PROSITE
PS50977, residues 4-64) plus a PsrA-specific C-terminal domain (PF17939 TetR_C_30,
IPR041586). No deep-research provider was available; PubMed MCP searches ("psrA
aeruginosa", "PsrA Pseudomonas aeruginosa fatty acid TetR structure") returned API
errors or no hits on 2026-11-05, so the review rests on the three cached papers
cited in GOA.

Literature

PsrA represses the fadBA5 beta-oxidation operon and long-chain fatty acids
relieve repression by disrupting PsrA DNA binding
PMID:18524913
(abstract only).
PsrA is an rpoS activator and negative autoregulator; it binds the motif
G/CAAAC N2-4 GTTTG/C and regulates further targets positively and negatively
PMID:15899403
PMID:15899403
(abstract only).
PsrA is required for full transcription of the T3SS regulatory operon exsCEBA
and binds its promoter with low affinity; secretion of T3SS effectors falls in
the deletion mutant and is restored by complementation
PMID:16428760
PMID:16428760
(full text read). The authors note that activation could be indirect
PMID:16428760.

Annotation notes

GO:0050714 positive regulation of protein secretion (IMP, PseudoCAP): the
secretion phenotype follows from reduced transcription of the T3SS genes.
Under GO's convention a transcription factor may be annotated to the process its
target genes carry out, so it is kept as non-core. No GO term exists for
regulation of type III secretion specifically.
MF: PsrA both represses and activates, so GO:0003700 (not repressor or activator)
is the appropriate MF level. Sequence-specific binding to a defined palindromic
motif supports GO:0000987 over GO:0000976 and GO:0003677.

PseudoCAP IBA-seed assessment

PsrA seeds the PTN004738546 GO:0006355 IBD (19 seeds) through its experimental
regulation rows; the PseudoCAP contribution is the IMP GO:0045893 row (a
descendant of GO:0006355). Two CollecTF rows (EXP, IDA GO:0045892) also support
the seeding, so PsrA's seed status does not rest on PseudoCAP. The node is shared
with nfxB, nalC, PA3678, atuR and nalD, reviewed in parallel; the shared-node
(GO_CENTRAL) verdict is recorded on those genes, and no duplicate GO_CENTRAL
defect is recorded here.

PTN node	node term	n_seeds	leaf IBAs	seed annotation (term, evidence, PMID)	other seeds	IBD stands without this seed?	verdict	rationale
PTN004738546	GO:0006355 regulation of DNA-templated transcription	19	411 (33 taxa)	GO:0045893 positive regulation of DNA-templated transcription, IMP, PMID:16428760 (PseudoCAP); also CollecTF GO:0045892 EXP PMID:18524913 and IDA PMID:15899403	18 others, incl. E. coli AcrR (P0ACS9), M. tuberculosis TetR regulators, P. aeruginosa mexZ, PA4596, PA3678	Yes	SOUND	Full text read. Transcriptional fusions in an in-frame deletion mutant, complementation, and EMSA binding of rPsrA to the exsCEBA promoter show that PsrA positively regulates exsCEBA transcription. Whether the activation is direct is left open by the authors, but GO:0045893 only needs PsrA to regulate transcription positively, and PsrA is an established DNA-binding regulator (fadBA5, rpoS, its own promoter). The generic node term suits a TetR clade. No PseudoCAP defect.

Shared-node verdict: recorded on nfxB/nalC/PA3678/atuR/nalD by the parallel review.