4YHG

NATIVE BACTEROIDETES-AFFILIATED GH5 CELLULASE LINKED WITH A POLYSACCHARIDE UTILIZATION LOCUS

Summary for 4YHG

• Entry DOI: 10.2210/pdb4yhg/pdb
• Related PRD ID: PRD_900021
• Descriptor: GH5, beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose (3 entities in total)
• Functional Keywords: beta alpha barrel, glycoside hydrolase, metagenomics, hydrolase
• Biological source: Bacteroidetes bacterium AC2a
• Total number of polymer chains: 2
• Total formula weight: 87751.64

Authors

Naas, A.E.,MacKenzie, A.K.,Dalhus, B.,Eijsink, V.G.H.,Pope, P.B. (deposition date: 2015-02-27, release date: 2015-07-15, Last modification date: 2024-01-10)

Primary citation

Naas, A.E.,MacKenzie, A.K.,Dalhus, B.,Eijsink, V.G.,Pope, P.B.
Structural Features of a Bacteroidetes-Affiliated Cellulase Linked with a Polysaccharide Utilization Locus.
Sci Rep, 5:11666-11666, 2015

PubMed Abstract: Previous gene-centric analysis of a cow rumen metagenome revealed the first potentially cellulolytic polysaccharide utilization locus, of which the main catalytic enzyme (AC2aCel5A) was identified as a glycoside hydrolase (GH) family 5 endo-cellulase. Here we present the 1.8 Å three-dimensional structure of AC2aCel5A, and characterization of its enzymatic activities. The enzyme possesses the archetypical (β/α)8-barrel found throughout the GH5 family, and contains the two strictly conserved catalytic glutamates located at the C-terminal ends of β-strands 4 and 7. The enzyme is active on insoluble cellulose and acts exclusively on linear β-(1,4)-linked glucans. Co-crystallization of a catalytically inactive mutant with substrate yielded a 2.4 Å structure showing cellotriose bound in the -3 to -1 subsites. Additional electron density was observed between Trp178 and Trp254, two residues that form a hydrophobic "clamp", potentially interacting with sugars at the +1 and +2 subsites. The enzyme's active-site cleft was narrower compared to the closest structural relatives, which in contrast to AC2aCel5A, are also active on xylans, mannans and/or xyloglucans. Interestingly, the structure and function of this enzyme seem adapted to less-substituted substrates such as cellulose, presumably due to the insufficient space to accommodate the side-chains of branched glucans in the active-site cleft.

PubMed: 26133573
DOI: 10.1038/srep11666

Experimental method

X-RAY DIFFRACTION (2.4 Å)