title: Structure of a novel thermostable GH51 α-L-arabinofuranosidase from Thermotoga petrophila RKU-1.
abstract: α-L-arabinofuranosidases (EC 3.2.1.55) participate in the degradation of a variety of L-arabinose-containing polysaccharides and interact synergistically with other hemicellulases in the production of oligosaccharides and bioconversion of lignocellulosic biomass into biofuels. In this work, the structure of a novel thermostable family 51 (GH51) α-L-arabinofuranosidase from Thermotoga petrophila RKU-1 (TpAraF) was determined at 3.1 Å resolution. The TpAraF tertiary structure consists of an (α/β)-barrel catalytic core associated with a C-terminal β-sandwich domain, which is stabilized by hydrophobic contacts. In contrast to other structurally characterized GH51 AraFs, the accessory domain of TpAraF is intimately linked to the active site by a long β-hairpin motif, which modifies the catalytic cavity in shape and volume. Sequence and structural analyses indicate that this motif is unique to Thermotoga AraFs. Small angle X-ray scattering investigation showed that TpAraF assembles as a hexamer in solution and is preserved at the optimum catalytic temperature, 65°C, suggesting functional significance. Crystal packing analysis shows that the biological hexamer encompasses a dimer of trimers and the multiple oligomeric interfaces are predominantly fashioned by polar and electrostatic contacts.
authors.affiliation: Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil.
authors.forename: Tatiana A C B
authors.initials: TA
authors.lastname: Souza
authors.forename: Camila R
authors.initials: CR
authors.lastname: Santos
authors.forename: Angelica R
authors.initials: AR
authors.lastname: Souza
authors.forename: Daiane P
authors.initials: DP
authors.lastname: Oldiges
authors.forename: Roberto
authors.initials: R
authors.lastname: Ruller
authors.forename: Rolf A
authors.initials: RA
authors.lastname: Prade
authors.forename: Fabio M
authors.initials: FM
authors.lastname: Squina
authors.forename: Mario T
authors.initials: MT
authors.lastname: Murakami
mesh_terms: D001419:Bacteria / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D004795:Enzyme Stability; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D001426:Bacterial Proteins; D006026:Glycoside Hydrolases; C019713:alpha-N-arabinofuranosidase