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Journal of Bacteriology, March 2000, p. 1499-1506, Vol. 182, No. 6
Department of Molecular Biosciences, Graduate
School of Bioagricultural Sciences, Nagoya University, Nagoya,
Aichi 464-8601,1 and Marine Resources
Department, Shikoku National Industrial Research Institute,
Takamatsu, Kagawa 761-0395,2 Japan
Received 10 September 1999/Accepted 17 December 1999
The exudate of germinated spores of B. cereus IFO 13597 in 0.15 M KCl-50 mM potassium phosphate (pH 7.0) contained a
spore-lytic enzyme which has substrate specificity for fragmented spore
cortex from wild-type organisms (cortical-fragment-lytic enzyme
[CFLE]), in addition to a previously characterized
germination-specific hydrolase which acts on intact spore cortex (spore
cortex-lytic enzyme [SCLE]) (R. Moriyama, S. Kudoh, S. Miyata, S. Nonobe, A. Hattori, and S. Makino, J. Bacteriol. 178:5330-5332, 1996).
CFLE was not capable of degrading isolated cortical fragments from spores of Bacillus subtilis ADD1, which lacks muramic acid
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Copyright © 2000, American Society for Microbiology. All rights reserved.
A Novel Spore Peptidoglycan Hydrolase of Bacillus
cereus: Biochemical Characterization and Nucleotide Sequence
of the Corresponding Gene, sleL
-lactam. This suggests that CFLE cooperates with SCLE in cortex
hydrolysis during germination. CFLE was purified in an active form and
identified as a 48-kDa protein which functions as an
N-acetylglucosaminidase. Immunochemical studies suggested
that the mature enzyme is localized on a rather peripheral region of
the dormant spore, probably the exterior of the cortex layer. A gene
encoding the enzyme, sleL, was cloned in Escherichia
coli, and the nucleotide sequence was determined. The gene
encodes a protein of 430 amino acids with a deduced molecular weight of
48,136. The N-terminal region contains a repeated motif common to
several peptidoglycan binding proteins. Inspection of the data banks
showed no similarity of CFLE with N-acetylglucosaminidases
found so far, suggesting that CFLE is a novel type of
N-acetylglucosaminidase. The B. subtilis genome sequence contains genes, yaaH and ydhD, which
encode putative proteins showing similarity to SleL.
*
Corresponding author. Mailing address: Department of
Molecular Biosciences, Graduate School of Bioagricultural Sciences,
Nagoya University, Nagoya, Aichi 464-8601, Japan. Phone: 81 (52)
789-4132. Fax: 81 (52) 789-4120. E-mail:
makino{at}nuagr1.agr.nagoya-u.ac.jp.
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