TenA_C family similar to the C-terminal TenA_C domain of Saccharomyces cerevisiae THI20 protein
This TenA family belongs to the TenA_C class as it has a conserved active site Cys residue; the double Glu residues identified in the active site of TenA_E from the archaeon Pyrococcus furiosus is conserved in this family. TenA_C proteins (EC 3.5.99.2) catalyze the hydrolysis of the thiamin breakdown product 4-amino-5-amino-methyl-2-methylpyrimidine (amino-HMP) to 4-amino-5-hydroxymethyl-2-methylpyrimidine (HMP) in a thiamin salvage pathway. Saccharomyces cerevisiae THI20 includes a C-terminal tetrameric TenA-like domain fused to an N-terminal HMP kinase/HMP-P kinase (ThiD-like) domain, and participates in thiamin biosynthesis, degradation and salvage; the TenA-like domain catalyzes the production of HMP from thiamin degradation products (salvage). A majority of this family are single-domain TenA_C- like proteins; some however have additional domains such as a ThiD domain. It has also been suggested that TenA proteins act as transcriptional regulators based on changes in gene-expression patterns when TenA is overexpressed in Bacillus subtilis, however this effect may be indirect.
Feature 1: conserved active site residues [active site], 3 residue positions
Conserved feature residue pattern:E C E
Evidence:
Comment:these proteins have a conserved active site Cys residue, and 2 conserved Glu residues in the active site; the Cys is thought to act as a nucleophile in the thiaminase reaction, Glu are thought to interact with the substituent at the 5-position of the pyrimidine ring
Jiyao W et al.(2023). "The conserved domain database in 2023.",