PP_5276 (UniProt Q88CA5) is a Pseudomonas putida KT2440 phospholipase D-superfamily protein with two PLD phosphodiesterase domains, each keeping the HxK(x4)D catalytic motif. It also carries a prokaryotic lipoprotein signature. PANTHER places it in the ClsC subfamily of cardiolipin synthases (PTHR21248:SF12) together with Escherichia coli ClsC, which, with its partner YmdB, forms cardiolipin by transferring a phosphatidyl group from phosphatidylethanolamine to phosphatidylglycerol. PP_5276 is therefore a probable third KT2440 cardiolipin synthase, alongside ClsA and ClsB. Its phosphatidyl donor and any partner requirement have not been tested.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0003824 catalytic activity | IEA GO_REF:0000002 | MODIFY | Summary: Catalytic activity is a root term, correct but less specific than the supported phosphatidyltransferase activity. Reason: The PLD/transphosphatidylase signature (IPR001736) and ClsC-subfamily membership support phosphatidyltransferase activity, the most specific term the evidence allows for this uncharacterized paralog. It is already carried by this gene. Proposed replacements: phosphatidyltransferase activity Supporting Evidence: file:PSEPK/PP_5276/PP_5276-uniprot.txt IPR001736; PLipase_D/transphosphatidylase. |
| GO:0030572 phosphatidyltransferase activity | IEA GO_REF:0000117 | ACCEPT | Summary: Phosphatidyltransferase activity, as precise as the evidence allows for this ClsC-subfamily protein. Reason: The protein has two PLD/transphosphatidylase domains with intact HxK(x4)D motifs and is classified in the ClsC subfamily. Every characterized member of PTHR21248 is a PLD-type phosphatidyltransferase. The donor is unresolved, though: ClsA/ClsB-type enzymes use PG (GO:0008808) and E. coli ClsC uses PE (GO:0090483). So the generic parent is the appropriate level. The ARBA source is not cited; support is the family and motif evidence. Supporting Evidence: file:PSEPK/PP_5276/PP_5276-uniprot.txt IPR001736; PLipase_D/transphosphatidylase. file:PSEPK/PP_5276/PP_5276-uniprot.txt PTHR21248:SF12; CARDIOLIPIN SYNTHASE C; 1. file:PSEPK/PP_5276/PP_5276-bioinformatics/RESULTS.md PP_5276 retains both PLD-superfamily HxK(x4)D catalytic motifs |
| GO:0032049 cardiolipin biosynthetic process | IEA GO_REF:0000120 | ACCEPT | Summary: Cardiolipin biosynthesis, inherited by TreeGrafter within the cardiolipin synthase family. Reason: PAINT places cardiolipin biosynthetic process at the PTHR21248 root (PTN000478698), seeded by characterized cardiolipin synthases from every subfamily with data, including E. coli ClsC of SF12, the subfamily that contains PP_5276. Both catalytic HKD motifs are intact at a spacing comparable to E. coli ClsC, whose His130 and His369 are needed for cardiolipin formation. The process holds whichever phosphatidyl donor is used. The exact reaction is left at phosphatidyltransferase level, and the in vivo contribution is a knowledge gap. Previous notes left this row UNDECIDED pending KT2440 data; the motif analysis and the family-wide process are judged sufficient for this process-level claim. Supporting Evidence: file:PSEPK/PP_5276/PP_5276-uniprot.txt PTHR21248:SF12; CARDIOLIPIN SYNTHASE C; 1. file:PSEPK/PP_5276/PP_5276-bioinformatics/RESULTS.md That spacing is comparable to E. coli ClsC (130 and 369, 239 apart) PMID:22988102 Mutation of the putative catalytic motif of ClsC prevents CL formation. |
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Download this section (compressed HTML)Q: Does PP_5276 catalyze the PE-plus-PG ClsC reaction in KT2440, and does it require a partner analogous to E. coli YmdB?
Q: Is the predicted lipoprotein signature of PP_5276 used, so that the enzyme is lipid-anchored rather than peripherally bound like E. coli ClsC?
Experiment: Reconstitute PP_5276 with PG and PE in proteoliposomes, test candidate partner proteins, and quantify cardiolipin in single and combinatorial synthase deletions.
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