Download MendeleyThe Structure and Function of an Arabinan-specific {alpha}-1,2-Arabinofuranosidase Identified from Screening the Activities of Bacterial GH43 Glycoside Hydrolases.
Cartmell, A., McKee, L.S., Pena, M.J., Larsbrink, J., Brumer, H., Kaneko, S., Ichinose, H., Lewis, R.J., Vikso-Nielsen, A., Gilbert, H.J., Marles-Wright, J.(2011) J Biological Chem 286: 15483-15495
- PubMed: 21339299 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1074/jbc.M110.215962
- Primary Citation Related Structures:
3QED, 3QEE, 3QEF - PubMed Abstract:
Reflecting the diverse chemistry of plant cell walls, microorganisms that degrade these composite structures synthesize an array of glycoside hydrolases. These enzymes are organized into sequence-, mechanism-, and structure-based families. Genomic data have shown that several organisms that degrade the plant cell wall contain a large number of genes encoding family 43 (GH43) glycoside hydrolases. Here we report the biochemical properties of the GH43 enzymes of a saprophytic soil bacterium, Cellvibrio japonicus, and a human colonic symbiont, Bacteroides thetaiotaomicron. The data show that C. japonicus uses predominantly exo-acting enzymes to degrade arabinan into arabinose, whereas B. thetaiotaomicron deploys a combination of endo- and side chain-cleaving glycoside hydrolases. Both organisms, however, utilize an arabinan-specific α-1,2-arabinofuranosidase in the degradative process, an activity that has not previously been reported. The enzyme can cleave α-1,2-arabinofuranose decorations in single or double substitutions, the latter being recalcitrant to the action of other arabinofuranosidases. The crystal structure of the C. japonicus arabinan-specific α-1,2-arabinofuranosidase, CjAbf43A, displays a five-bladed β-propeller fold. The specificity of the enzyme for arabinan is conferred by a surface cleft that is complementary to the helical backbone of the polysaccharide. The specificity of CjAbf43A for α-1,2-l-arabinofuranose side chains is conferred by a polar residue that orientates the arabinan backbone such that O2 arabinose decorations are directed into the active site pocket. A shelflike structure adjacent to the active site pocket accommodates O3 arabinose side chains, explaining how the enzyme can target O2 linkages that are components of single or double substitutions.
- Institute for Cell and Molecular Biosciences, Newcastle University, The Medical School, Newcastle upon Tyne NE2 4HH, United Kingdom.
Organizational Affiliation:
