PP_4677 encodes a predicted integral-membrane CDP-diacylglycerol--serine O-phosphatidyltransferase. The eight-pass enzyme represents the type-II PssA architecture and is predicted to transfer the phosphatidyl group of CDP-diacylglycerol to L-serine, forming phosphatidylserine for subsequent decarboxylation to phosphatidylethanolamine by Psd.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003882 CDP-diacylglycerol-serine O-phosphatidyltransferase activity | IEA GO_REF:0000003 | ACCEPT | Summary: The EC 2.7.8.8 reaction, IPR004533 assignment, and specific PTHR14269:SF61 subfamily all identify a type-II phosphatidylserine synthase. Reason: GO:0003882 captures the predicted donor and L-serine acceptor specificity of Q88DZ1 and is the most informative available molecular-function term. Supporting Evidence: file:PSEPK/PP_4677/PP_4677-uniprot.txt DR GO; GO:0003882; F:CDP-diacylglycerol-serine O-phosphatidyltransferase activity; IEA:UniProtKB-EC. file:PSEPK/PP_4677/PP_4677-notes.md Q88DZ1 carries the specific IPR004533 and PTHR14269:SF61 phosphatidylserine synthase assignments. file:PSEPK/PP_4677/PP_4677-deep-research-openscientist.md PP_4677 (UniProt Q88DZ1) encodes phosphatidylserine synthase (PssA; EC 2.7.8.8), the enzyme that catalyzes the committed, identity-defining step of the de novo pathway to phosphatidylethanolamine (PE) in *Pseudomonas putida* KT2440. |
| GO:0008654 phospholipid biosynthetic process | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: Phosphatidylserine formation is a phospholipid-biosynthetic reaction, but this term does not identify the downstream phosphatidylethanolamine branch. Reason: Retain the valid parent process while using GO:0006646 to represent the specific consecutive PssA-Psd pathway. |
| GO:0016020 membrane | IEA GO_REF:0000120 | MODIFY | Summary: UniProt predicts eight transmembrane helices and describes Q88DZ1 as a multi-pass membrane protein. Reason: Integral-membrane topology is strongly supported and is characteristic of the type-II PssA architecture. In this bacterium, plasma membrane is the informative specific replacement for the generic membrane term. Proposed replacements: plasma membrane Supporting Evidence: file:PSEPK/PP_4677/PP_4677-notes.md PP_4677 is an eight-pass membrane protein predicted to form phosphatidylserine from CDP-diacylglycerol and L-serine. |
| GO:0016780 phosphotransferase activity, for other substituted phosphate groups | IEA GO_REF:0000120 | MARK AS OVER ANNOTATED | Summary: This broad phosphotransferase term is compatible with the reaction but omits the CDP-diacylglycerol donor and L-serine acceptor. Reason: GO:0003882 captures the same predicted activity with informative substrate specificity. |
| GO:0006646 phosphatidylethanolamine biosynthetic process | IC file:PSEPK/PP_4677/PP_4677-notes.md | NEW | Summary: PP_4677 is a candidate phosphatidylserine synthase supplying the consecutive Psd reaction in the two-step phosphatidylethanolamine route. Reason: The accepted reaction assignment and the reconstructed KT2440 pathway support this more specific process term. Supporting Evidence: file:PSEPK/PP_4677/PP_4677-notes.md The phosphatidylserine product supplies the consecutive Psd reaction in phosphatidylethanolamine biosynthesis. |
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Download this section (compressed HTML)Q: Do Q88DZ1 and Q88GQ4 contribute redundantly or under different growth conditions to phosphatidylserine production?
Suggested experts: bacterial lipid biochemist, Pseudomonas physiologist
Experiment: Compare single and double deletion strains for phosphatidylserine-synthase activity, phosphatidylserine and phosphatidylethanolamine lipid abundance, and complementation by each candidate.
Hypothesis: Q88DZ1 and Q88GQ4 both catalyze phosphatidylserine formation but differ in their relative physiological contribution or condition dependence.
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