pfam10120: ThiN (This model is not part of the current CDD release)
Thiamine-phosphate synthase ThiN
This entry represents thiamine-phosphate synthase ThiN which condenses 4-methyl-5-(beta-hydroxyethyl)thiazole monophosphate (THZ-P) and 4-amino-5-hydroxymethyl pyrimidine pyrophosphate (HMP-PP) to form thiamine monophosphate (TMP). Vitamin B1 (thiamine pyrophosphate) is involved in several microbial metabolic functions. Thiamine biosynthesis is accomplished by joining two intermediate molecules that are synthesized separately, HMP-PP and HET-P. In the archaeon Natrialba magadii, ThiE and ThiN, are known to join HMP-PP ( hydroxymethylpyrimidine pyrophosphate) and HET-P (hydroxyethylthiazole phosphate) to generate thiamine phosphate. Whereas ThiE in Natrialba magadii is a mono-functional protein, ThiN exists as a C-terminal domain in a ThiDN fusion protein - examples of all three forms, from various prokaryotes, are found in this entry. Another example is the transcriptional repressor ThiR from Haloferax volcanii which contains a ThiN domain but it is catalytically inactive as it lacks the conserved Met residue found in the extended alpha-helix near the active site His in ThiN. Moreover, it was shown that thiamine biosynthesis in archaea is regulated by ThiR and not by a riboswitch.
Jiyao W et al.(2023). "The conserved domain database in 2023.",