Crystal structure of a UDP-GlcNAc epimerase for surface polysaccharide biosynthesis in Acinetobacter baumannii

Bhumika S. Shah, Heather E. Ashwood, Stephen J. Harrop, Daniel N. Farrugia, Ian T. Paulsen, Bridget C. Mabbutt*

*Corresponding author for this work

Research output: Contribution to journalArticle

13 Downloads (Pure)

Abstract

With new strains of Acinetobacter baumannii undergoing genomic analysis, it has been possible to define regions of genomic plasticity (RGPs), encoding specific adaptive elements. For a selected RGP from a community-derived isolate of A. baumannii, we outline sequences compatible with biosynthetic machinery of surface polysaccharides, specifically enzymes utilized in the dehydration and conversion of UDP-N-acetyl-D-glucosamine (UDP-D-GlcNAc). We have determined the crystal structure of one of these, the epimerase Ab-WbjB. This dehydratase belongs to the 'extended' short-chain dehydrogenase/reductase (SDR) family, related in fold to previously characterised enzymes CapE and FlaA1. Our 2.65Å resolution structure of Ab-WbjB shows a hexamer, organised into a trimer of chain pairs, with coenzyme NADP+ occupying each chain. Specific active-site interactions between each coenzyme and a lysine quaternary group of a neighbouring chain interconnect adjacent dimers, so stabilising the hexameric form. We show UDP-GlcNAc to be a specific substrate for Ab-WbjB, with binding evident by ITC (Ka = 0.23 μmol-1). The sequence of Ab-WbjB shows variation from the consensus active-site motifs of many SDR enzymes, demonstrating a likely catalytic role for a specific threonine sidechain (as an alternative to tyrosine) in the canonical active site chemistry of these epimerases.

Original languageEnglish
Article numbere0191610
Pages (from-to)1-19
Number of pages19
JournalPLoS ONE
Volume13
Issue number1
DOIs
Publication statusPublished - 19 Jan 2018

Bibliographical note

Copyright the Author(s) 2018. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Fingerprint Dive into the research topics of 'Crystal structure of a UDP-GlcNAc epimerase for surface polysaccharide biosynthesis in Acinetobacter baumannii'. Together they form a unique fingerprint.

Cite this