title: Crystal structures of substrate-bound chitinase from the psychrophilic bacterium Moritella marina and its structure in solution.
abstract: The four-domain structure of chitinase 60 from Moritella marina (MmChi60) is outstanding in its complexity. Many glycoside hydrolases, such as chitinases and cellulases, have multi-domain structures, but only a few have been solved. The flexibility of the hinge regions between the domains apparently makes these proteins difficult to crystallize. The analysis of an active-site mutant of MmChi60 in an unliganded form and in complex with the substrates NAG4 and NAG5 revealed significant differences in the substrate-binding site compared with the previously determined complexes of most studied chitinases. A SAXS experiment demonstrated that in addition to the elongated state found in the crystal, the protein can adapt other conformations in solution ranging from fully extended to compact.
authors.affiliation: Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland.
authors.forename: Piotr H
authors.initials: PH
authors.lastname: Malecki
authors.affiliation: Department of Biochemistry and Molecular Biology, National and Kapodistrian University of Athens, Zografou Campus, 157 01 Athens, Greece.
authors.forename: Constantinos E
authors.initials: CE
authors.lastname: Vorgias
authors.affiliation: Hamburg Unit, EMBL c/o DESY, European Molecular Biology Laboratory, Notkestrasse 85, 22607 Hamburg, Germany.
authors.forename: Maxim V
authors.initials: MV
authors.lastname: Petoukhov
authors.affiliation: Hamburg Unit, EMBL c/o DESY, European Molecular Biology Laboratory, Notkestrasse 85, 22607 Hamburg, Germany.
authors.forename: Dmitri I
authors.initials: DI
authors.lastname: Svergun
authors.affiliation: Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Rypniewski
mesh_terms: D002688:Chitinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D018360:Crystallography, X-Ray; D008024:Ligands; D034221:Moritella / Q000201:enzymology* / Q000235:genetics; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D017354:Point Mutation; D011487:Protein Conformation; D055503:Protein Multimerization; D053838:Scattering, Small Angle; D012996:Solutions; D013379:Substrate Specificity; D014961:X-Ray Diffraction
chemical_list: D008024:Ligands; D009844:Oligosaccharides; D012996:Solutions; C012238:chitotetrose; D002688:Chitinases
keywords: Ig-like domain; SAXS; TIM β/α-barrel; chitin; chitin-binding domain; chitinase; flexibility; hinge regions; ligand binding; multi-domain; psychrophilic