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opt rdg 2 - On the Process of Cellular Division in...

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Escherichia coli Also Lacking DNA Polymerase Activity Deoxynucleoside Triphosphates by DNA Thermosensitive Mutants of On the Process of Cellular Division in Escherichia coli, V. Incorporation of Jose Mordoh, Yukinori Hirota, and Francois Jacob doi:10.1073/pnas.67.2.773 1970;67;773-778 PNAS This information is current as of January 2007. www.pnas.org#otherarticles This article has been cited by other articles: E-mail Alerts . click here article or article - sign up in the box at the top right corner of the Receive free email alerts when new articles cite this Rights & Permissions www.pnas.org/misc/rightperm.shtml entirety, see: To reproduce this article in part (figures, tables) or in Reprints www.pnas.org/misc/reprints.shtml To order reprints, see: Notes:
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Proceedings of the National Academy of Sciences Vol. 67, No. 2, pp. 773-778, October 1970 On the Process of Cellular Division in Escherichia coli, V. Incorporation of Deoxynucleoside Triphosphates by DNA Thermosensitive Mutants of Escherichia coli Also Lacking DNA Polymerase Activity* Jose Mordoh t, Yukinori Hirota, and Francois Jacob SERVICE DE. GINkTIQUE CELLULAIRE DE L'INSTITUT PASTEUR ET DU COLLIGE DE FRANCE, PARIS Communicated July 28, 1970 Abstract. Double mutants of Escherichia coli were constructed by combining DNA thermosensitive mutations affecting either DNA initiation (DnaA) or elongation (DnaB) with the Pol Al mutation, which abolishes DNA polymerase activity. Incorporation of labeled deoxynucleoside triphosphates was studied in these mutants using toluene-treated cells. This incorporation was found to be exactly correlated with the capacity of the mutants to synthesize DNA in vivo. The process of chromosome replication can be divided into two steps: initia- tion of DNA synthesis and elongation of the molecule. Thermosensitive mutants have been isolated that are unable to perform one or the other process at high temperature.1-4 Until recently, however, no biochemical defect, either in the DNA polymerase or in the establishment of the nucleotide pools, could be cor- related with the genetic lesion of such mutants." 2'4 This result, taken together with a variety of arguments indicating that chromosome duplication is likely to occur in the membrane, suggested that DNA polymerase is not the enzyme involved in this process. This was reinforced by the isolation5 of a mutant (W3110 P3478 Pol Al-) lacking DNA polymerase but still able to multiply. In addition, the availability of such a mutant offers a new possibility for the biochemical investigation of DNA thermosensitive mutants. In this paper we report (1) a method for detecting the incorporation of deoxynucleoside triphos- phates (dNTPs) in toluene-treated bacteria and (2) the behavior at permissive and nonpermissive temperatures of double mutants carrying both a Pol Al mutation and a thermosensitive DNA-synthesis mutation.
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