4axn | pdb_00004axn

Hallmarks of processive and non-processive glycoside hydrolases revealed from computational and crystallographic studies of the Serratia marcescens chitinases

spinqualitylabelsall models 4axn, resolution 1.68Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4axn is a 2 chain structure with sequence from Serratia marcescens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.68Å Ligands: ACT, CA Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q700B8_SERMA Publication Abstract from PubMed Degradation of recalcitrant polysaccharides in nature is typically accomplished by mixtures of processive and nonprocessive glycoside hydrolases (GHs), which exhibit synergistic activity wherein nonprocessive enzymes provide new sites for productive attachment of processive enzymes. GH processivity is typically attributed to active site geometry, but previous work has demonstrated that processivity can be tuned by point mutations or removal of single loops. To gain additional insights into the differences between processive and nonprocessive enzymes that give rise to their synergistic activities, this study reports the crystal structure of the catalytic domain of the GH family 18 nonprocessive endochitinase, ChiC, from Serratia marcescens. This completes the structural characterization of the co-evolved chitinolytic enzymes from this bacterium and enables structural analysis of their complementary functions. The ChiC catalytic module reveals a shallow substrate-binding cleft that lacks aromatic residues vital for processivity, a calcium-binding site not previously seen in GH18 chitinases, and, importantly, a displaced catalytic acid (Glu-141), suggesting flexibility in the catalytic center. Molecular dynamics simulations of two processive chitinases (ChiA and ChiB), the ChiC catalytic module, and an endochitinase from Lactococcus lactis show that the nonprocessive enzymes have more flexible catalytic machineries and that their bound ligands are more solvated and flexible. These three features, which relate to the more dynamic on-off ligand binding processes associated with nonprocessive action, correlate to experimentally measured differences in processivity of the S. marcescens chitinases. These newly defined hallmarks thus appear to be key dynamic metrics in determining processivity in GH enzymes complementing structural insights. Hallmarks of Processivity in Glycoside Hydrolases from Crystallographic and Computational Studies of the Serratia marcescens Chitinases.,Payne CM, Baban J, Horn SJ, Backe PH, Arvai AS, Dalhus B, Bjoras M, Eijsink VG, Sorlie M, Beckham GT, Vaaje-Kolstad G J Biol Chem. 2012 Oct 19;287(43):36322-30. doi: 10.1074/jbc.M112.402149. Epub, 2012 Sep 5. PMID:22952223 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Chitinase 3D structures

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