6rwf

The dissociation mechanism of processive cellulasesThe dissociation mechanism of processive cellulases

Structural highlights 6rwf is a 1 chain structure with sequence from Trichoderma reesei QM6a. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.64Å Ligands: , , Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function G0RVK1_HYPJQ Publication Abstract from PubMed Cellulase enzymes deconstruct recalcitrant cellulose into soluble sugars, making them a biocatalyst of biotechnological interest for use in the nascent lignocellulosic bioeconomy. Cellobiohydrolases (CBHs) are cellulases capable of liberating many sugar molecules in a processive manner without dissociating from the substrate. Within the complete processive cycle of CBHs, dissociation from the cellulose substrate is rate limiting, but the molecular mechanism of this step is unknown. Here, we present a direct comparison of potential molecular mechanisms for dissociation via Hamiltonian replica exchange molecular dynamics of the model fungal CBH, Trichoderma reesei Cel7A. Computational rate estimates indicate that stepwise cellulose dethreading from the binding tunnel is 4 orders of magnitude faster than a clamshell mechanism, in which the substrate-enclosing loops open and release the substrate without reversing. We also present the crystal structure of a disulfide variant that covalently links substrate-enclosing loops on either side of the substrate-binding tunnel, which constitutes a CBH that can only dissociate via stepwise dethreading. Biochemical measurements indicate that this variant has a dissociation rate constant essentially equivalent to the wild type, implying that dethreading is likely the predominant mechanism for dissociation. The dissociation mechanism of processive cellulases.,Vermaas JV, Kont R, Beckham GT, Crowley MF, Gudmundsson M, Sandgren M, Stahlberg J, Valjamae P, Knott BC Proc Natl Acad Sci U S A. 2019 Oct 30. pii: 1913398116. doi:, 10.1073/pnas.1913398116. PMID:31666327 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Glucanase 3D structures

spinqualitylabelsall models 6rwf, resolution 1.64Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image