title: Modular hyperthermostable bacterial endo-β-1,4-mannanase: molecular shape, flexibility and temperature-dependent conformational changes.
abstract: Endo-β-1,4-mannanase from Thermotoga petrophila (TpMan) is a hyperthermostable enzyme that catalyzes the hydrolysis of β-1,4-mannoside linkages in various mannan-containing polysaccharides. A recent study reported that TpMan is composed of a GH5 catalytic domain joined by a linker to a carbohydrate-binding domain. However, at this moment, there is no three-dimensional structure determined for TpMan. Little is known about the conformation of the TpMan as well as the role of the length and flexibility of the linker on the spatial arrangement of the constitutive domains. In this study, we report the first structural characterization of the entire TpMan by small-angle X-ray scattering combined with the three-dimensional structures of the individual domains in order to shed light on the low-resolution model, overall dimensions, and flexibility of this modular enzyme at different temperatures. The results are consistent with a linker with a compact structure and that occupies a small volume with respect to its large number of amino acids. Furthermore, at 20°C the results are consistent with a model where TpMan is a molecule composed of three distinct domains and that presents some level of molecular flexibility in solution. Even though the full enzyme has some degree of molecular flexibility, there might be a preferable conformation, which could be described by the rigid-body modeling procedure. Finally, the results indicate that TpMan undergoes a temperature-driven transition between conformational states without a significant disruption of its secondary structure. Our results suggest that the linker can optimize the geometry between the other two domains with respect to the substrate at high temperatures. These studies should provide a useful basis for future biophysical studies of entire TpMan.
authors.affiliation: Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), Santo André, São Paulo, Brazil.
authors.forename: Viviam M
authors.initials: VM
authors.lastname: da Silva
authors.affiliation: Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), Santo André, São Paulo, Brazil.
authors.forename: Francieli
authors.initials: F
authors.lastname: Colussi
authors.affiliation: Departamento de Física e Biofísica, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, São Paulo, Brazil.
authors.forename: Mario
authors.initials: M
authors.lastname: de Oliveira Neto
authors.affiliation: Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), Santo André, São Paulo, Brazil.
authors.forename: Antonio S K
authors.initials: AS
authors.lastname: Braz
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Fabio M
authors.initials: FM
authors.lastname: Squina
authors.affiliation: Instituto de Física, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Cristiano L P
authors.initials: CL
authors.lastname: Oliveira
authors.affiliation: Centro de Ciências Naturais e Humanas, Universidade Federal do ABC (UFABC), Santo André, São Paulo, Brazil.
authors.forename: Wanius
authors.initials: W
authors.lastname: Garcia
mesh_terms: D001419:Bacteria / Q000201:enzymology*; D002942:Circular Dichroism; D000067493:Dynamic Light Scattering; D006863:Hydrogen-Ion Concentration; D008361:Mannosidases / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D053838:Scattering, Small Angle; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D008361:Mannosidases; C041867:endo-1,4-beta-D-mannanase