Structural highlights
Publication Abstract from PubMedN-acetylated sugars are often found, for example, on the lipopolysaccharides of Gram-negative bacteria, on the S-layers of Gram-positive bacteria, and on capsular polysaccharides. Key enzymes involved in their biosynthesis are the sugar N-acetyltransferases. Here we describe a structural and functional analysis of one such enzyme from Helicobacter pullorum, an emerging pathogen that may be associated with gastroenteritis and gall bladder and liver diseases. For this analysis, the gene BA919-RS02330 putatively encoding an N-acetyltransferase was cloned, and the corresponding protein was expressed and purified. A kinetic analysis demonstrated that the enzyme utilizes dTDP-3-amino-3,6-dideoxy-d-glucose as a substrate as well as dTDP-3-amino-3,6-dideoxy-d-galactose, albeit at a reduced rate. In addition to this kinetic analysis, a similar enzyme from Helicobacter bilis was also cloned and expressed, and its kinetic parameters were determined. Seven X-ray crystallographic structures of various complexes of the H. pullorum wild-type enzyme (or the C80T variant) were determined to resolutions of 1.7 a or higher. The overall molecular architecture of the H. pullorum N-acetyltransferase places it into the Class II left-handed beta-helix superfamily (LbetaH). Taken together the data presented herein suggest that 3-acetamido-3,6-dideoxy-d-glucose (or the galactose derivative) is found on either the H. pullorum O-antigen or in another of its complex glycoconjugates. A BLAST search suggests that more than 50 non-pylori Helicobacter spp. have genes encoding N-acetyltransferases. Given that there is little information concerning the complex glycans in non-pylori Helicobacter spp. and considering their zoonotic potential, our results provide new biochemical insight into these pathogens. This article is protected by copyright. All rights reserved. Biochemical Investigation of an N-acetyltransferase from Helicobacter pullorum.,Griffiths WA, Spencer KD, Thoden JB, Holden HM Protein Sci. 2021 Oct 15. doi: 10.1002/pro.4207. PMID:34651380[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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