THI5 (YFL058W, P43534) review notes

Identity

• HMP-P synthase THI5; NMT1/THI5 family; homodimer; Fe cofactor [UniProt:P43534].
• One of four subtelomeric paralogues THI5/THI11/THI12/THI13 PMID:12777485. THI5, THI11 and THI12 differ at only 1-3 of 340 positions (ungapped comparison of the UniProt sequences in this batch).

Function

• Structure/function of yeast Thi5p; PLP is a substrate, iron essential [PMID:23048037 "Mutational and yeast complementation studies identify the key residues for HMP-P biosynthesis as well as the use of pyridoxal 5'-phosphate as a substrate rather than as a cofactor."; "we could show that iron binding to HMP-P synthase is essential for the reaction"].
• Candida albicans orthologue: His66 of the enzyme is the histidine source; single turnover PMID:22568620.
• Genetic redundancy of the four paralogues PMID:12777485.
• RSP5 WW-domain protein-array interaction (PMID:16606443): high-throughput; no functional meaning established.

Curation conclusions

• Core MF GO:0106344 HMP-P synthase activity from histidine and PLP; BP GO:0009228 thiamine biosynthetic process; location not determined experimentally (presumed cytosol; ND for CC retained).
• THI5 donates its own His side chain, so it does the chemistry of the step (participant, not merely necessary).
• YeastCyc PWY3O-17 lists only THI13 for this step; THI5/THI11/THI12 are missing.