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Replication of bacteriophage PM2 deoxyribonucleic acid: A closed circular double-stranded molecule

Espejo, Romilio T. and Canelo, Eliana S. and Sinsheimer, Robert L. (1971) Replication of bacteriophage PM2 deoxyribonucleic acid: A closed circular double-stranded molecule. Journal of Molecular Biology, 56 (3). pp. 597-621. ISSN 0022-2836. doi:10.1016/0022-2836(71)90404-9.

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Shortly after infection with bacteriophage PM2, host DNA synthesis is inhibited while synthesis of the supercoiled viral DNA begins at a low rate. This rate increases at about ten minutes after infection to reach a value that is thereafter maintained until lysis of the cells. Pulse-chase experiments suggest the existence of several precursors of supercoiled PM2 DNA. Two of them, one which sediments as nicked circular PM2 DNA (21 s) and another, appearing earlier in time, sedimenting 1.15 times faster (24 s), have been partially characterized. The 24 s component seems to contain linear single strands both longer and shorter than the strands of PM2 DNA. It has been purified, examined in the electron microscope and shown to consist of double-stranded rings of the circumference of PM2 DNA, with one double-stranded DNA branch of distinct length, but always shorter than PM2 DNA. From these characteristics the 24 s precursor seems to be a PM2 DNA molecule with a growing chain in accordance with the hypothesis that chain growth involves addition of nucleotides to the end of one parental strand while a second strand is initiated de novo. The pulse-labeled precursor which sediments like nicked circular PM2 DNA does not contain label in single-strand rings but only in open strands. Experiments based on transfer of the infected cell from heavy to light medium suggest a mechanism of replication which involves random selection of the viral DNA molecule to be duplicated from among these present in the cell.

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Additional Information:© 1971 Elsevier Ltd. Received 6 May 1970, Revised 13 October 1970, This research was supported by grant GM13554 from the U.S. Public Health Service. We should like to thank Dr J. W. Sedat and Mr R. L. Hallberg for valuable advice on performing the hybridization experiments and Mr J.M. Jordan for making available the procedure for electron microscopy of DNA and allowing us to describe it here.
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U.S. Public Health Service (USPHS)GM 13554
Issue or Number:3
Record Number:CaltechAUTHORS:20160803-094401346
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Official Citation:Romilio T. Espejo, Eliana S. Canelo, Robert L. Sinsheimer, Replication of bacteriophage PM2 deoxyribonucleic acid: A closed circular double-stranded molecule, Journal of Molecular Biology, Volume 56, Issue 3, 28 March 1971, Pages 597-614, IN15-IN16, 615-621, ISSN 0022-2836, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:69403
Deposited By: Ruth Sustaita
Deposited On:03 Aug 2016 23:49
Last Modified:11 Nov 2021 04:13

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