title: Cloning, purification, crystallization and preliminary X-ray studies of a carbohydrate-binding module from family 64 (StX).
abstract: In recent years, biofuels have attracted great interest as a source of renewable energy owing to the growing global demand for energy, the dependence on fossil fuels, limited natural resources and environmental pollution. However, the cost-effective production of biofuels from plant biomass is still a challenge. In this context, the study of carbohydrate-binding modules (CBMs), which are involved in guiding the catalytic domains of glycoside hydrolases to polysaccharides, is crucial for enzyme development. Aiming at the structural and functional characterization of novel CBMs involved in plant polysaccharide deconstruction, an analysis of the CAZy database was performed and CBM family 64 was chosen owing to its capacity to bind with high specificity to microcrystalline cellulose and to the fact that is found in thermophilic microorganisms. In this communication, the CBM-encoding module named StX was expressed, purified and crystallized, and X-ray diffraction data were collected from native and derivatized crystals to 1.8 and 2.0 Å resolution, respectively. The crystals, which were obtained by the hanging-drop vapour-diffusion method, belonged to space group P3121, with unit-cell parameters a = b = 43.42, c = 100.96 Å for the native form. The phases were found using the single-wavelength anomalous diffraction method.
authors.affiliation: Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brazil.
authors.forename: Bruna Medeia
authors.initials: BM
authors.lastname: Campos
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brazil.
authors.forename: Marcelo Vizona
authors.initials: MV
authors.lastname: Liberato
authors.affiliation: Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil.
authors.forename: Igor
authors.initials: I
authors.lastname: Polikarpov
authors.affiliation: Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brazil.
authors.forename: Ana Carolina de Mattos
authors.initials: AC
authors.lastname: Zeri
authors.affiliation: Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brazil.
authors.forename: Fabio Marcio
authors.initials: FM
authors.lastname: Squina
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D001665:Binding Sites; D003001:Cloning, Molecular; D003460:Crystallization; D018360:Crystallography, X-Ray; D013142:Spirochaeta / Q000737:chemistry* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins
keywords: accessory domain; carbohydrate-binding module