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Journal of Bacteriology, March 2001, p. 1773-1779, Vol. 183, No. 5
Laboratory of Biochemistry, Institute of
Chemistry B6, University of Liege, B-4000 Liege,
Belgium1; Enzyme Technology Division,
Institute of Molecular Biology and Biotechnology, and Department of
Biology, Division of Applied Biology and Biotechnology, University
of Crete, Heraklion, Crete, Greece2;
National and Kapodistrian University of Athens, Faculty of
Biology, Department of Biochemistry-Molecular Biology,
Panepistimiopolis-Zographou, 15701 Athens,
Greece3; and Laboratoire de
Microbiologie du Froid, Institut Universitaire de Technologie,
27000 Evreux, France4
Received 14 August 2000/Accepted 6 December 2000
Arthrobacter sp. strain TAD20, a chitinolytic
gram-positive organism, was isolated from the sea bottom along the
Antarctic ice shell. Arthrobacter sp. strain TAD20 secretes
two major chitinases, ChiA and ChiB (ArChiA and
ArChiB), in response to chitin induction. A single
chromosomal DNA fragment containing the genes coding for both
chitinases was cloned in Escherichia coli. DNA sequencing analysis of this fragment revealed two contiguous open reading frames coding for the precursors of ArChiA (881 amino acids
[aa]) and ArChiB (578 aa). ArChiA and
ArChiB are modular enzymes consisting of a
glycosyl-hydrolase family 18 catalytic domain as well as two and one
chitin-binding domains, respectively. The catalytic domain of
ArChiA exhibits 55% identity with a chitodextrinase from
Vibrio furnissii. The ArChiB catalytic domain
exhibits 33% identity with chitinase A of Bacillus
circulans. The ArChiA chitin-binding domains are
homologous to the chitin-binding domain of ArChiB. ArChiA and ArChiB were purified to homogeneity
from the native Arthrobacter strain and partially
characterized. Thermal unfolding of ArChiA,
ArChiB, and chitinase A of Serratia marcescens
was studied using differential scanning calorimetry.
ArChiA and ArChiB, compared to their mesophilic
counterpart, exhibited increased heat lability, similar to other
cold-adapted enzymes.
0021-9193/01/$04.00+0 DOI: 10.1128/JB.183.5.1773-1779.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Cloning, Sequences, and Characterization of Two
Chitinase Genes from the Antarctic Arthrobacter sp. Strain
TAD20: Isolation and Partial Characterization of the Enzymes
*
Corresponding author. Mailing address: Department of
Biology, Division of Applied Biology and Biotechnology, University of Crete, P.O. Box 1470, Heraklion 71110, Crete, Greece. Phone: 30 81 394375. Fax: 30 81 394375. E-mail:
bouriotis{at}imbb.forth.gr.
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