3ibx
Crystal structure of F47Y variant of TenA (HP1287) from Helicobacter pylori
Structural highlights
FunctionTENA_HELPX Catalyzes an amino-pyrimidine hydrolysis reaction at the C5' of the pyrimidine moiety of thiamine compounds to give a hydroxymethylpyrimidine (HMP). Displays low activity on 4-amino-5-aminomethyl-2-methylpyrimidine as substrate, indicating that the enzyme may act on a different HMP precursor that may derive from the human stomach food assumption or processing. Is probably involved in thiamine biosynthesis. Does not display thiaminase II activity, as it is unable to hydrolyze thiamine.[1] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedHP1287 (tenA) from Helicobacter pylori is included among the genes that play a relevant role in bacterium colonization and persistence. The gene has been cloned and its product, protein TenA, has been expressed and purified. The crystal structures of the wild-type protein and the mutant F47Y have been determined at resolutions of 2.7 and 2.4 A, respectively. The molecular model, a homotetramer with 222 symmetry, shows that the H. pylori TenA structure belongs to the thiaminase II class of proteins. These enzymes were recently found to be involved in a salvage pathway for the synthesis of the thiamin precursor hydroxypyrimidine, which constitutes a building block in thiamin biosynthesis, in particular in bacteria living in the soil. By contrast, enzymatic measurements on TenA from H. pylori indicate that the activity on the putative substrate 4-amino-5-aminomethyl-2-methylpyrimidine is very modest. Moreover, in the present study, we demonstrate that the mutation at residue 47, a position where a phenylalanine occurs in all the strains of H. pylori sequenced to date, is not sufficient to explain the very low catalytic activity toward the expected substrate. As a result of differences in the colonization environment of H. pylori as well as the TenA structural and catalytic peculiar features, we suggest a possible pivotal role for the H. pylori enzyme in the thiamin biosynthetic route, which is in agreement with the relevance of this protein in the stomach colonization process. Structural and mutational analysis of TenA protein (HP1287) from the Helicobacter pylori thiamin salvage pathway - evidence of a different substrate specificity.,Barison N, Cendron L, Trento A, Angelini A, Zanotti G FEBS J. 2009 Nov;276(21):6227-35. Epub 2009 Sep 23. PMID:19780837[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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