title: Cj1123c (PglD), a multifaceted acetyltransferase from Campylobacter jejuni.
abstract: Campylobacter jejuni produces both N- and O-glycosylated proteins. Because protein glycosylation contributes to bacterial virulence, a thorough characterization of the enzymes involved in protein glycosylation is warranted to assess their potential use as therapeutic targets and as glyco-engineering tools. We performed a detailed biochemical analysis of the molecular determinants of the substrate and acyl-donor specificities of Cj1123c (also known as PglD), an acetyltransferase of the HexAT superfamily involved in N-glycosylation of proteins. We show that Cj1123c has acetyl-CoA-dependent N-acetyltransferase activity not only on the UDP-4-amino-4,6-dideoxy-GlcNAc intermediate of the N-glycosylation pathway but also on the UDP-4-amino-4,6-dideoxy-AltNAc intermediate of the O-glycosylation pathway, implying functional redundancy between both pathways. We further demonstrate that, despite its somewhat relaxed substrate specificity for N-acetylation, Cj1123c cannot acetylate aminoglycosides, indicating a preference for sugar-nucleotide substrates. In addition, we show that Cj1123c can O-acetylate UDP-GlcNAc and that Cj1123c is very versatile in terms of acyl-CoA donors as it can use propionyl- and butyryl-CoA instead of acetyl-CoA. Finally, using structural information available for Cj1123c and related enzymes, we identify three residues (H125, G143, and G173) involved in catalysis and (or) acyl-donor specificity, opening up possibilities of tailoring the specificity of Cj1123c for the synthesis of novel sugars.
authors.affiliation: Department of Microbiology and Immunology, Infectious Diseases Research Group, University of Western Ontario, London, ON, Canada.
authors.forename: Melinda
authors.initials: M
authors.lastname: Demendi
authors.forename: Carole
authors.initials: C
authors.lastname: Creuzenet
mesh_terms: D000107:Acetylation; D000123:Acetyltransferases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence; D001483:Base Sequence; D016123:Campylobacter jejuni / Q000201:enzymology*; D002850:Chromatography, Gel; D017931:DNA Primers; D006639:Histidine / Q000737:chemistry; D008958:Models, Molecular; D016296:Mutagenesis; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D017931:DNA Primers; D006639:Histidine; D000123:Acetyltransferases