1CHK

STREPTOMYCES N174 CHITOSANASE PH5.5 298K

Summary for 1CHK

• Entry DOI: 10.2210/pdb1chk/pdb
• Descriptor: CHITOSANASE (2 entities in total)
• Functional Keywords: anti-fungal protein, hydrolase, o-glycosyl, hydrolase (o-glycosyl)
• Biological source: Streptomyces sp.
• Cellular location: Secreted: P33665
• Total number of polymer chains: 2
• Total formula weight: 51697.54

Authors

Marcotte, E.M.,Robertus, J.D. (deposition date: 1995-06-12, release date: 1996-07-11, Last modification date: 2024-02-07)

Primary citation

Marcotte, E.M.,Monzingo, A.F.,Ernst, S.R.,Brzezinski, R.,Robertus, J.D.
X-ray structure of an anti-fungal chitosanase from streptomyces N174.
Nat.Struct.Biol., 3:155-162, 1996

PubMed 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.

PubMed: 8564542
DOI: 10.1038/nsb0296-155

Experimental method

X-RAY DIFFRACTION (2.4 Å)