4m98

Publication Abstract from PubMed

UDP-N,N'-diacetylbacillosamine (UDP-diNAcBac) is a unique carbohydrate produced by a number of bacterial species and has been implicated in pathogenesis. The terminal step in the formation of this important bacterial sugar is catalyzed by an AcCoA-dependent acetyltransferase in both N- and O-linked protein glycosylation pathways. This bacterial acetyltransferase is a member of the left-handed beta-helix family and forms a homotrimer as the functional unit. While previous endeavors have focused on the Campylobacter jejuni acetyltransferase (PglD) from the N-linked glycosylation pathway, structural characterization of the homologous enzymes in the O-linked glycosylation pathways is lacking. Herein, we present the apo crystal structures of the acetyltransferase domain (ATD) from the bifunctional enzyme PglB (Neisseria gonorrhoeae) and the full-length acetyltransferase WeeI (Acinetobacter baumannii). Additionally, a PglB-ATD structure was solved in complex with AcCoA. Surprisingly, this structure reveals a contrasting binding mechanism for this substrate when compared to the AcCoA-bound PglD structure. A comparison between these findings with the previously solved PglD crystal structures illustrates a dichotomy among N- and O-linked glycosylation pathway enzymes. Based upon these structures, key residues in the UDP-4-amino and AcCoA binding pockets were mutated to determine their effect on binding and catalysis in PglD, PglB-ATD, and WeeI. Lastly, a phylogenetic analysis of the aforementioned acetyltransferases was employed to illuminate the diversity among N- and O-linked glycosylation pathway enzymes.

Biochemical analysis and structure determination of bacterial acetyltransferases responsible for the biosynthesis of UDP-N,N'-diacetylbacillosamine.,Morrison MJ, Imperiali B J Biol Chem. 2013 Sep 24. PMID:24064219^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.