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|Title:||A β-mannannase with a lysozyme fold and a novel molecular catalytic mechanism|
Portela de Souza, Leticia
Gilbert, Harry J.
Rovira i Virgili, Carme
Goddard-Borger, Ethan D.
Davies, Gideon J.
|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: https://doi.org/10.1021/acscentsci.6b00232|
|It is part of:||ACS Central Science, 2016, vol. 2, num. 12, p. 896-903|
|Appears in Collections:||Articles publicats en revistes (Química Inorgànica i Orgànica)|
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