PP_3394

Summary: The enzyme-family evidence supports broad catalytic activity despite unresolved reaction specificity.

Reason: The DRE-TIM/HMGL-like and alpha-isopropylmalate/homocitrate-synthase signatures imply catalysis. Their disagreement concerns substrate and reaction class, not whether PP_3394 is catalytic; no target-specific loss of catalysis has been established.

Summary: The HMGL-like domain supports this possibility, but the sequence lacks the HMG-CoA lyase PROSITE signature found in MvaB.

Reason: An alpha-isopropylmalate/homocitrate-synthase signature creates a paralog-specificity conflict that a first pass cannot resolve. The existing BCAA module report explicitly leaves PP_3394 versus mvaB unresolved; the mvaB report also does not assign a reaction to PP_3394. TreeGrafter source PTN000031316 is recorded as an unresolved transfer, not a demonstrated target-specific loss.

Summary: This pathway assignment depends on the unresolved HMG-CoA lyase activity.

Reason: Do not infer a leucine-catabolic role from the shared fold alone. The existing BCAA module report explicitly leaves PP_3394 versus mvaB unresolved; the mvaB report also does not assign a reaction to PP_3394. TreeGrafter source PTN000031316 is recorded as an unresolved transfer, not a demonstrated target-specific loss.

Summary: Oxo-acid lyase activity depends on an unresolved reaction-class assignment.

Reason: GO:0016833 specifies nonhydrolytic, nonoxidative C-C cleavage of a 3-hydroxy acid (QuickGO definition checked 2026-09-20). HMG-CoA cleavage fits, whereas a synthase-family assignment alone does not establish this cleavage activity. This uncertainty is about chemistry, not excessive generality.

Summary: The alpha-isopropylmalate/homocitrate-synthase signature supports an acyl-transfer reaction family.

Reason: The physiological substrate and exact activity have not been established.

Summary: Ketone-body production would follow only if PP_3394 is an HMG-CoA lyase.

Reason: The underlying molecular-function assignment is unresolved. The existing BCAA module report explicitly leaves PP_3394 versus mvaB unresolved; the mvaB report also does not assign a reaction to PP_3394. TreeGrafter source PTN000031316 is recorded as an unresolved transfer, not a demonstrated target-specific loss.