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Title: A β-mannannase with a lysozyme fold and a novel molecular catalytic mechanism
Author: Jin, Yi
Petricevic, Marija
John, Alan
Raich, Lluís
Jenkins, Huw
Portela de Souza, Leticia
Cuskin, Fiona
Gilbert, Harry J.
Rovira i Virgili, Carme
Goddard-Borger, Ethan D.
Williams, Spencer
Davies, Gideon J.
Keywords: Lisozim
Issue Date: 8-Nov-2016
Publisher: American Chemical Society
Abstract: The enzymatic cleavage of β-1,4-mannans is achieved by endo-β-1,4-mannanases, enzymes involved in germination of seeds and microbial hemicellulose degradation, and which have increasing industrial and consumer product applications. β-Mannanases occur in a range of families of the CAZy sequence-based glycoside hydrolase (GH) classification scheme including families 5, 26, and 113. In this work we reveal that β-mannanases of the newly described GH family 134 differ from other mannanase families in both their mechanism and tertiary structure. A representative GH family 134 endo-β-1,4-mannanase from a Streptomyces sp. displays a fold closely related to that of hen egg white lysozyme but acts with inversion of stereochemistry. A Michaelis complex with mannopentaose, and a product complex with mannotriose, reveal ligands with pyranose rings distorted in an unusual inverted chair conformation. Ab initio quantum mechanics/molecular mechanics metadynamics quantified the energetically accessible ring conformations and provided evidence in support of a 1C4 → 3H4 → 3S1 conformational itinerary along the reaction coordinate. This work, in concert with that on GH family 124 cellulases, reveals how the lysozyme fold can be co-opted to catalyze the hydrolysis of different polysaccharides in a mechanistically distinct manner
Note: Reproducció del document publicat a:
It is part of: ACS Central Science, 2016, vol. 2, num. 12, p. 896-903
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ISSN: 2374-7951
Appears in Collections:Articles publicats en revistes (Química Inorgànica i Orgànica)

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