Identification of the cpdA Gene Encoding Cyclic 3′,5′-Adenosine Monophosphate Phosphodiesterase in Escherichia coli*
- Ryu Imamura‡,
- Kunitoshi Yamanaka‡,
- Teru Ogura‡,
- Sota Hiraga‡,
- Nobuyuki Fujita§,
- Akira Ishihama§ and
- Hironori Niki‡¶
- From the ‡ Department of Molecular Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University School of Medicine, Kumamoto, Kumamoto 862 and the
- § Department of Molecular Genetics, National Institute of Genetics, Mishima, Shizuoka 411, Japan
- ↵¶ To whom correspondence should be addressed. Tel.: 81-96-373-5335; Fax: 81-96-371-2408; E-mail: niki{at}gpo.kumamoto-u.ac.jp
Abstract
We have identified a gene, cpdA, located at 66.2 min of the chromosome of Escherichia coli that encodes cyclic 3′,5′-adenosine monophosphate phosphodiesterase (cAMP phosphodiesterase, EC3.1.4.17). The expression of β-galactosidase, which is a product of the lacZ gene, was repressed in cells that harbored multiple copies of the plasmid carrying the cpdA gene. Northern blotting showed that the transcription of the lacZ gene was inhibited in these cells. Multiple copies of the cpdA gene decreased the intracellular concentration of cAMP, which is a positive regulator for transcription of the lacZ gene. We found that the purified CpdA protein repressed in vitro transcription from the lacP1 promoter by decreasing cAMP. In addition, we showed that the CpdA protein hydrolyzed cAMP to 5′-adenosine monophosphate and that its activity was activated by iron. Our results suggested that regulation of intracellular concentration of cAMP is dependent not only on synthesis of cAMP but also on hydrolysis of cAMP by cAMP phosphodiesterase.
Footnotes
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↵* This work was supported by Grants-in-Aid for Scientific Research on Priority Areas, Grants-in-Aid for Scientific Research B, Monbusho International Scientific Research Program for Joint Research from the Ministry of Education, Science, Sports and Culture of Japan, and the Okukubo Memorial Fund for Medical Research in Kumamoto University School of Medicine (to R. I.). The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) D16557[GenBank].
- Received November 13, 1995.
- Revision received June 21, 1996.
- © 1996 by The American Society for Biochemistry and Molecular Biology, Inc.
