X-ray structure of an anti-fungal chitosanase from streptomyces N174.
Nat Struct Biol
; 3(2): 155-62, 1996 Feb.
Article
em En
| MEDLINE
| ID: mdl-8564542
ABSTRACT
We report the 2.4 A X-ray crystal structure of a protein with chitosan endo-hydrolase activity isolated from Streptomyces N174. The structure was solved using phases acquired by SIRAS from a two-site methyl mercury derivative combined with solvent flattening and non-crystallographic two-fold symmetry averaging, and refined to an R-factor of 18.5%. The mostly alpha-helical fold reveals a structural core shared with several classes of lysozyme and barley endochitinase, in spite of a lack of shared sequence. Based on this structural similarity we postulate a putative active site, mechanism of action and mode of substrate recognition. It appears that Glu 22 acts as an acid and Asp 40 serves as a general base to activate a water molecule for an SN2 attack on the glycosidic bond. A series of amino-acid side chains and backbone carbonyl groups may bind the polycationic chitosan substrate in a deep electronegative binding cleft.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Streptomyces
/
Glicosídeo Hidrolases
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Nat Struct Biol
Assunto da revista:
BIOLOGIA MOLECULAR
Ano de publicação:
1996
Tipo de documento:
Article
País de afiliação:
Estados Unidos