Mimosine Arrests DNA Synthesis at Replication Forks by Inhibiting Deoxyribonucleotide Metabolism (*)
- David M. Gilbert(2)(§),
- Ann Neilson(1),
- Hiroshi Miyazawa(2)(¶),
- Melvin L. DePamphilis(2) and
- William C. Burhans(1)(**)
- From the (1) Department of Molecular and Cellular Biology, Roswell Park Cancer Institute, Buffalo, New York 14263 and the
- (2) Roche Institute of Molecular Biology, Roche Research Center, Nutley, New Jersey 07110
- ** To whom correspondence should be addressed. Tel.: 716-845-7691; Fax: 716-845-8169.
Abstract
Mimosine has been reported to specifically prevent initiation of DNA replication in the chromosomes of mammalian nuclei. To test this hypothesis, the effects of mimosine were examined in several DNA replication systems and compared with the effects of aphidicolin, a specific inhibitor of replicative DNA polymerases. Our results demonstrated that mimosine inhibits DNA synthesis in mitochondrial, nuclear, and simian virus 40 (SV40) genomes to a similar extent. Furthermore, mimosine and aphidicolin were indistinguishable in their ability to arrest SV40 replication forks and mammalian nuclear chromosomal replication forks. In contrast to aphidicolin, mimosine did not inhibit DNA replication in lysates of mammalian cells supplied with exogenous deoxyribonucleotide triphosphate precursors for DNA synthesis. Mimosine also had no effect on initiation or elongation of DNA replication in Xenopus eggs or egg extracts containing high levels of deoxyribonucleotide triphosphates. In parallel with its inhibitory effect on DNA synthesis in mammalian cells, mimosine altered deoxyribonucleotide triphosphate pools in a manner similar to that reported for another DNA replication inhibitor that affects deoxyribonucleotide metabolism, hydroxyurea. Taken together, these results show that mimosine inhibits DNA synthesis at the level of elongation of nascent chains by altering deoxyribonucleotide metabolism.
Footnotes
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↵¶ On leave from the Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-01, Japan and was supported in part by a grant from the Biodesign Research Program sponsored by RIKEN.
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↵* This work was supported in part by National Institutes of Health Grant CA16056 and by Roswell Alliance. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 The abbreviations used are:
- CHO
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Chinese hamster ovary
- kb
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kilobase(s).
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↵2 W. Burhans, unpublished results.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
