Journal of Molecular Biology
Volume 178, Issue 2, 15 September 1984, Pages 227-236
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Multiple origin usage for DNA replication in sdrA(rnh) mutants of Escherichia coli K-12: Initiation in the absence of oriC

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Abstract

In stable DNA replication (sdrA/rnh) mutants of Escherichia coli, initiation of rounds of DNA replication occurs in the absence of the normal origin of replication. oriC. To determine whether or not the initiation occurs at a fixed site(s) on the chromosome in sdrA mutants, the DNA from exponentially growing sdrA mutant cells with or without the oriC site (ΔoriC) was analyzed for the relative copy numbers of various genes along the chromosome. The results suggest that there are at least four fixed sites or regions of the sdrA ΔoriC chromosome from which DNA replication can be initiated in the absence of the oriC sequence.

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    A major part of this work was performed during the good summer of 1983 when T.K. visited the laboratory of Jean-Michel Louarn in Toulouse. This work was supported by a grant from the Action Thématique Programmée, CNRS-INRA “Microbiologie” no. 9575 and by grants from the National Institutes of Health (GM22092 and MBS grant PR08139) and a grant-in-aid for research from University of New Mexico to T.K.

    Present address: Laboratory of Molecular Genetics, National Institutes of Health, Bethesda, MD 20205, U.S.A.

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