ThiR controlls thiamine biosynthesis and transport genes in diverse lineages in the Crenarchaeota phylum as well as in the Halobacteria and Thermococci classes of the Euryarchaeota. ThiR regulators are composed of an N-terminal DNA-binding domain and a C-terminal ligand-binding domain. In addition to thiamine biosynthesis genes, the reconstructed ThiR regulons include various transporters for thiamine and its precursors. The thiamine phosphate effector pathway is part of the broader thiamine (vitamin B1) biosynthetic system and is regulated by the transcriptional regulator ThiR ThiR is a DNA-binding transcriptional regulator that senses thiamine phosphate levels and controls the expression of genes involved in thiamine precursor biosynthesis and recycling. When thiamine phosphate levels are low, ThiR activates expression of its target genes to restore adequate levels of thiamine derivatives. Key genes in the ThiR regulog include: thi4 – Encodes thiazole synthase, a key enzyme that catalyzes the formation of the thiazole moiety of thiamine. Thi4 is essential for de novo thiamine biosynthesis and contains an iron-sulfur cluster involved in sulfur transfer. thiDN – A fusion gene encoding two enzymatic activities: ThiD: A hydroxymethylpyrimidine kinase that phosphorylates pyrimidine intermediates in the thiamine biosynthesis pathway. ThiN: Functions in downstream phosphorylation and conversion of thiamine intermediates, supporting their incorporation into TMP and ultimately TPP.

Thiamine phosphate References