TIGR00748: HMG_CoA_syn_Arc (this model, PSSM-Id:129831 is obsolete and has been replaced by 273250)
hydroxymethylglutaryl-CoA synthase, putative
This family of archaeal proteins shows considerable homology and identical active site residues to the bacterial hydroxymethylglutaryl-CoA synthase (HMG-CoA synthase, modeled by TIGR01835) which is the second step in the mevalonate pathway of IPP biosynthesis. An enzyme from Pseudomonas fluorescens involved in the biosynthesis of the polyketide diacetyl-phloroglucinol is more closely related, but lacks the active site residues. In each of the genomes containing a member of this family there is no other recognized HMG-CoA synthase, although other elements of the mevalonate pathway are in evidence. The only archaeon currently sequenced which lacks a homolog in this pathway is Halobacterium, which _does_ contain a separate HMG-CoA synthase. Thus, although there is no experimental evidence supporting this name, the bioinformatics-based conclusion appears to be sound [Fatty acid and phospholipid metabolism, Biosynthesis].