Affiliation:
1. Department of Microbiology, Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan
Abstract
ABSTRACT
Alteromonas
sp. strain O-7 secretes four chitinases (ChiA, ChiB, ChiC, and ChiD) in the presence of chitin. To elucidate why the strain produces multiple chitinases, we studied the expression levels of the four genes and proteins, their enzymatic properties, and their synergistic effects on chitin degradation. Among the four chitinases, ChiA was produced in the largest quantities, followed by ChiD, and the production of ChiB and ChiC changed at lower levels than those of ChiA and ChiD. The expression of the
chiA
,
chiB
,
chiC
, and
chiD
genes was investigated at the transcriptional level. The RNA transcript of
chiA
was most strongly induced in the presence of chitin, the expression of
chiD
followed, and the RNA transcripts of
chiB
and
chiC
changed at low levels. The hydrolyzing activities of the four chitinases against various substrates were examined. ChiA was the most active enzyme against powdered chitin, whereas ChiC was the most active against soluble chitin among the four chitinases. ChiD had activities closer to those of ChiA than to those of ChiB and ChiC. ChiB showed no distinctive feature against the chitinous substrates tested. When powdered chitin was treated with the proper combination of four chitinases, an approximately 2.0-fold increase in the hydrolytic activity was observed. These results, together with the results described above, indicate that ChiA plays a central role in chitin degradation for this strain.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
54 articles.
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