TAILIEUCHUNG - Báo cáo khoa học: Characterization of a b-N-acetylhexosaminidase and a b-N-acetylglucosaminidase/b-glucosidase from Cellulomonas fimi

The Gram-positive soil bacteriumCellulomonas fimiis shown to produce at least two intracellular b-N-acetylglucosaminidases, a family 20 b-N-acetyl-hexosaminidase (Hex20), and a novel family 3-b-N-acetylglucosamini-dase⁄b-glucosidase (Nag3), through screening of a genomic expression library, cloning of genes and analysis of their sequences. | ềFEBS Journal Characterization of a p-N-acetylhexosaminidase and a p-N-acetylglucosaminidase p-glucosidase from Cellulomonas fimi Christoph Mayer1 2 3 David J. VoGadlc Melanie Mah2 Karen Rupitz1 Dominik Stoll2 R. A. J. Warren2 and Stephen G. Withers1 1 Department of Chemistry University of British Columbia Vancouver Canada 2 Department of Microbiology Immunology University of British Columbia Vancouver Canada 3 Department of Biology University of Konstanz Germany Keywords bifunctionalglycosidase cellwallrecycling chitin metabolism murein peptidoglycan Correspondence C. Mayer Department of Biology University of Konstanz 78457 Konstanz Germany Fax 49 7531 88 3356 Tel 49 7531 88 4854 E-mail Present address Department of Molecular Biology and Biochemistry Simon Fraser University Burnaby BC Canada Database The nucleotide sequences listed in this paper have been submitted to the DDBJ EMBL GenBank database under the accession numbers AF478459 and AF478460 Received 22 February 2006 revised 3 May 2006 accepted 4 May 2006 doi The Gram-positive soil bacterium Cellulomonas fimi is shown to produce at least two intracellular b-N-acetylglucosaminidases a family 20 b-N-acetyl-hexosaminidase Hex20 and a novel family 3-b-N-acetylglucosamini-dase b-glucosidase Nag3 through screening of a genomic expression library cloning of genes and analysis of their sequences. Nag3 exhibits broad substrate specificity for substituents at the C2 position of the gly-cone kcat Km values at 25 C were s 1-mM 1 and s 1-mM 1 for 4 -nitrophenyl b-N-acetyl-D-glucosaminide and 4 -nitrophenyl b-D-glu-coside respectively. The first glycosidase with this broad specificity to be described Nag3 suggests an interesting evolutionary link between b-N-ace-tylglucosaminidases and b-glucosidases of family 3. Reaction by a doubledisplacement mechanism was confirmed for Nag3 through the identification of a glycosyl-enzyme species trapped with the .

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