Structural basis for thermostability of endo-1,5-alpha-L-arabinanase from Bacillus thermodenitrificans TS-3.
The crystal structure of a thermostable endo-1,5-alpha-L-arabinanase, ABN-TS, from Bacillus thermodenitrificans TS-3 was determined at 1.9 A to an R-factor of 18.3% and an R-free-factor of 22.5%. The enzyme molecule has a five-bladed beta-propeller fold. The substrate-binding cleft formed across one face of the propeller is open on both sides to allow random binding of several sugar units in the polymeric substrate arabinan. The beta-propeller fold is stabilized through a ring closure. ABN-TS exhibits a new closure-mode involving residues in the N-terminal region: Phe7 to Gly21 exhibit hydrogen bonds and hydrophobic interactions with the first and last blades, and Phe4 links the second and third blades through a hydrogen bond and an aromatic stacking interaction, respectively. The role of the N-terminal region in the thermostability was confirmed with a mutant lacking 16 amino acid residues from the N-terminus of ABN-TS.
Yamaguchi
Asako
A
Research Institute for Advanced Science and Technology, Osaka Prefecture University, Sakai, Osaka 599-8570.
Tada
Toshiji
T
Wada
Kei
K
Nakaniwa
Tetsuko
T
Kitatani
Tomoya
T
Sogabe
Yuri
Y
Takao
Makoto
M
Sakai
Takuo
T
Nishimura
Keiichiro
K
D001407:Bacillus / Q000201:enzymology; D018360:Crystallography, X-Ray; D004795:Enzyme Stability; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000235:genetics; D006358:Hot Temperature; D008958:Models, Molecular; D020836:Protein Structure, Quaternary
D006026:Glycoside Hydrolases; C082526:arabinan endo-1,5-alpha-L-arabinosidase