title: Correlation of temperature induced conformation change with optimum catalytic activity in the recombinant G/11 xylanase A from Bacillus subtilis strain 168 (1A1).
abstract: The 1.7A resolution crystal structure of recombinant family G/11 beta-1,4-xylanase (rXynA) from Bacillus subtilis 1A1 shows a jellyroll fold in which two curved beta-sheets form the active-site and substrate-binding cleft. The onset of thermal denaturation of rXynA occurs at 328 K, in excellent agreement with the optimum catalytic temperature. Molecular dynamics simulations at temperatures of 298-328 K demonstrate that below the optimum temperature the thumb loop and palm domain adopt a closed conformation. However, at 328 K these two domains separate facilitating substrate access to the active-site pocket, thereby accounting for the optimum catalytic temperature of the rXynA.
authors.affiliation: Department of Physics, IBILCE/UNESP, Cristovão Colombo 2265, São José do Rio Preto, São Paulo, Brazil.
authors.forename: Mário T
authors.initials: MT
authors.lastname: Murakami
authors.forename: Raghuvir K
authors.initials: RK
authors.lastname: Arni
authors.forename: Davi S
authors.initials: DS
authors.lastname: Vieira
authors.forename: Léo
authors.initials: L
authors.lastname: Degrève
authors.forename: Roberto
authors.initials: R
authors.lastname: Ruller
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Ward
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology*; D001665:Binding Sites; D002384:Catalysis; D003461:Crystallography; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry*; D006358:Hot Temperature; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011489:Protein Denaturation; D011994:Recombinant Proteins / Q000737:chemistry; D013696:Temperature
chemical_list: D011994:Recombinant Proteins; D043364:Endo-1,4-beta Xylanases