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J. Biol. Chem., Vol. 276, Issue 13, 10564-10569, March 30, 2001
From the Department of Life Sciences, Graduate School of Arts and
Sciences, University of Tokyo, Komaba, Meguro, Tokyo 153, Japan
A novel gene encoding an adenylyl cyclase,
designated cyaG, was identified in the filamentous
cyanobacterium Spirulina platensis. The predicted
amino acid sequence of the C-terminal region of cyaG was
similar to the catalytic domains of Class III adenylyl and guanylyl
cyclases. The N-terminal region next to the catalytic domain of CyaG
was similar to the dimerization domain, which is highly conserved among
guanylyl cyclases. As a whole, CyaG is more closely related to guanylyl
cyclases than to adenylyl cyclases in its primary structure. The
catalytic domain of CyaG was expressed in Escherichia coli
and partially purified. CyaG showed adenylyl cyclase (but not guanylyl
cyclase) activity. By site-directed mutagenesis of three amino acid
residues (Lys533, Ile603, and
Asp605) within the purine ring recognition site of CyaG to
Glu, Arg, and Cys, respectively, CyaG was transformed to a guanylyl
cyclase that produced cGMP instead of cAMP. Thus having properties of both cyclases, CyaG may therefore represent a critical position in the
evolution of Class III adenylyl and guanylyl cyclases.
The nucleotide sequence reported in this paper has been submitted
to the DDBJ/GenBankTM/EBI Data Bank with
accession number D49531.
To whom correspondence should be addressed. Tel.: 81-3-5454-6631;
Fax: 81-3-5454-4333; E-mail: cohmori@mail.ecc.u-tokyo.ac.jp.
Copyright © 2001 by The American Society for Biochemistry and Molecular Biology, Inc. This article has been cited by other articles:
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