Bacterial glutamate-to-P5C branch of proline biosynthesis

Species-neutral bacterial module for the two-enzyme conversion of L-glutamate to L-glutamate 5-semialdehyde, which cyclizes to 1-pyrroline-5-carboxylate (P5C), during proline biosynthesis. ProB phosphorylates L-glutamate to L-glutamyl 5-phosphate, and ProA reduces that acyl phosphate intermediate to L-glutamate 5-semialdehyde using NADPH. This module deliberately stops before the terminal P5C reductase step that makes L-proline.

First-pass PSEPK interpretation: proB and proA satisfy the glutamate-to-P5C branch but not the complete L-proline biosynthesis pathway, which also needs a P5C reductase/ProC-type terminal step. Keep the misleading KEGG carbapenem-biosynthesis label out of the module biology. The parent families PTHR43654 and PTHR11063 are valid, function-named families. Their current subfamily assignments are not asserted: PTHR43654:SF1 is labeled ISOPENTENYL PHOSPHATE KINASE, while PTHR11063:SF8 is labeled for fused DELTA-1-PYRROLINE-5-CARBOXYLATE SYNTHASE. Q88Q07 GOA nevertheless carries GO:0004349 with PTN002462614; the local PAINT slice places loss of that activity and gain of GO:0102043 at the distinct IRD-marked PTN001337743 isopentenyl-phosphate-kinase clade. Q88DL4 GOA carries GO:0004350 with PTN002253185. These GOA PTNs provide PSEPK descent context but are not asserted as ancestral nodes because they are absent from the committed PAINT slices; the verified family-level IBD nodes remain PTN000115542 and PTN000115463.