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: PP_3394 is a divergent DRE-TIM metallolyase that lacks the HMG-CoA-lyase-specific signature; the verified leucine/terpene HMG-CoA lyase in KT2440 is MvaB/PP_3540.

Reason: The focused paralog analysis resolved the conflict left by the first pass. PP_3394 retains the DRE-TIM catalytic core but fails the HMG-CoA-lyase-specific PROSITE signature and carries an isopropylmalate/homocitrate-synthase-like motif, whereas MvaB/PP_3540 is an ortholog-level match to the experimentally characterized P. aeruginosa LiuE. This IEA row is a specific HMG-CoA lyase claim, not a generic DRE-TIM catalytic claim, so the correct action for PP_3394 is removal. The same report cautions that the PP_3394-specific discriminator remains computational because PP_3394 itself lacks a direct biochemical assay or mutant phenotype.

Summary: The leucine-catabolic HMG-CoA-lyase role maps to MvaB/PP_3540, not to PP_3394.

Reason: The focused DRE-TIM report found that MvaB/PP_3540, not PP_3394, is the ortholog of the experimentally verified P. aeruginosa LiuE. PP_3394 has neither ortholog-level identity to LiuE nor a leucine/terpene-degradation neighborhood, so this electronic leucine-catabolism row is a paralog over-transfer through the shared HMGL-like fold. This removal rests on computational paralog discrimination rather than a direct PP_3394 assay.

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: PP_3394 matches a synthase-family PS00815 signature and LRDG motif, but the exact acyl-transfer reaction remains unassayed.

Reason: The focused report moves PP_3394 away from the HMG-CoA lyase signature and toward isopropylmalate/homocitrate-synthase-like condensation chemistry by PS00815 and N-terminal LRDG motif matches. Those computational motifs support the acyl-alkyl transfer family assignment, but they do not establish the physiological substrate or exact activity.

Summary: Acetoacetate formation by HMG-CoA lyases does not establish a dedicated ketone-body biosynthetic process, and the KT2440 HMG-CoA lyase maps to MvaB/PP_3540 rather than PP_3394.

Reason: The bacterial leucine/terpene terminal reaction is catabolic rather than ketone-body biosynthesis, and the computational PP_3394/MvaB discriminator assigns that HMG-CoA-lyase chemistry to MvaB/PP_3540. PP_3394 itself still lacks a direct assay or mutant phenotype, but the ARBA whole-pathway process transfer is unsupported either way.