Thiazole biosynthetic enzyme, prokaryotic (IPR022828)

Short name: Thi4_prok

Overlapping homologous superfamilies

Family relationships


This entry represents bacterial and archaeal proteins related to eukaryotic THI4, involved in the biosynthesis of the thiamine precursor thiazole.

Archaea harbour structural homologues of both the bacterial (ThiS-ThiF) and eukaryotic (THI4) proteins for thiazole synthesis. Most archaea have homologues that cluster to the THI4 family of proteins, but lack the conserved cysteine residue of the yeast THI4p that is required for sulfur transfer in formation of the thiazole ring. Instead, they have a histidine residue that is well conserved. Initially, these archaeal histidine-cointaining THI4 homologues were reported to convert ribose-1,5-bisphosphate (R15P) into ribulose-1,5-bisphosphate, the substrate of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) [PMID: 15375115], but this may not be correct and their function remains unknown [PMID: 25348237]. On the other hand, archaeal THI4 homologues with a conserved catalytic cysteine are linked to thiamine biosynthesis [PMID: 25348237].

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.