TAILIEUCHUNG - Báo cáo khoa học: Crystal structure and enzymatic properties of a bacterial family 19 chitinase reveal differences from plant enzymes

We describe the cloning, overexpression, purification, characterization and crystal structure of chitinase G, a single-domain family 19 chitinase from the Gram-positive bacterium Streptomyces coelicolorA3(2). Although chi-tinase G was not capable of releasing 4-methylumbelliferyl from artificial chitooligosaccharide substrates, it was capable of degrading longer chito-oligosaccharides at rates similar to those observed for other chitinases. | ỊFEBS Journal Crystal structure and enzymatic properties of a bacterial family 19 chitinase reveal differences from plant enzymes Ingunn A. Hoell1 Bj0rn Dalhus2 Ellinor B. Heggset1 Stein I. Aspmo1 and Vincent G. H. Eijsink1 1 Department of Chemistry Biotechnology and Food Science Norwegian University of Life Sciences As Norway 2 Institute of MedicalMicrobiology Section for Molecular Biology NationalUniversity Hospital Oslo Norway Keywords ChiG chitinase family 19 Streptomyces coelicolor A3 2 subsite structure Correspondence V. G. H. Eijsink Department of Chemistry Biotechnology and Food Science Norwegian University of Life Sciences PO Box 5003 1432 As Norway Fax 47 64965901 Tel 47 64965892 E-mail Received 6 June 2006 revised 1 September 2006 accepted 4 September 2006 doi We describe the cloning overexpression purification characterization and crystal structure of chitinase G a single-domain family 19 chitinase from the Gram-positive bacterium Streptomyces coelicolor A3 2 . Although chitinase G was not capable of releasing 4-methylumbelliferyl from artificial chitooligosaccharide substrates it was capable of degrading longer chito-oligosaccharides at rates similar to those observed for other chitinases. The enzyme was also capable of degrading a colored colloidal chitin substrate carboxymethyl-chitin-remazol-brilliant violet and a small presumably amorphous subfraction of a-chitin and b-chitin but was not capable of degrading crystalline chitin completely. The crystal structures of chitinase G and a related Streptomyces chitinase chitinase C Kezuka Y Ohishi M Itoh Y Watanabe J Mitsutomi M Watanabe T Nonaka T 2006 J Mol Biol 358 472-484 showed that these bacterial family 19 chitinases lack several loops that extend the substrate-binding grooves in family 19 chitinases from plants. In accordance with these structural features detailed analysis of the degradation of chitooligosaccharides by chitinase G showed that

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