Structural insights into xylanase mutant 254RL1 for improved activity and lower pH optimum.
Enzyme Microb Technol
; 147: 109786, 2021 Jun.
Article
en En
| MEDLINE
| ID: mdl-33992408
ABSTRACT
Xylanases degrade xylan to valuable end products. In our previous study, the alkaline xylanase S7-xyl from Bacillus halodurans S7 was engineered by rational design and the best mutant xylanase 254RL1 exhibited 3.4-fold improvements in specific activity at pH 9.0. Further research found that the enzyme activity at pH 6.0 was almost 2-fold than that at pH 9.0. To elucidate the reason of enhanced performance of 254RL1 at decreased pH optimum, we determined the X-ray crystal structure of 254RL1 at 2.21 Å resolution. The structural analysis revealed that the mutations enlarged the opening of the access tunnel and shortened the tunnel. Moreover, the mutations changed the hydrogen bond network around the catalytic residue and decreased the pKa value of acid-base catalyst E159 which reduced the pH optimum of the xylanase. The result provided the basis for the acid-alkaline engineering of the glycoside hydrolases.
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1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Bacillus
/
Endo-1,4-beta Xilanasas
Idioma:
En
Revista:
Enzyme Microb Technol
Año:
2021
Tipo del documento:
Article