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Accumulation of large non-circular forms of the chromosome in recombination-defective mutants of Escherichia coli

BACKGROUND: Double-strand breakage of chromosomal DNA is obviously a serious threat to cells because various activities of the chromosome depend on its integrity. However, recent experiments suggest that such breakage may occur frequently during "normal" growth in various organisms – from...

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Autores principales: Handa, Naofumi, Kobayashi, Ichizo
Formato: Texto
Lenguaje:English
Publicado: BioMed Central 2003
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC156651/
https://www.ncbi.nlm.nih.gov/pubmed/12718760
http://dx.doi.org/10.1186/1471-2199-4-5
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author Handa, Naofumi
Kobayashi, Ichizo
author_facet Handa, Naofumi
Kobayashi, Ichizo
author_sort Handa, Naofumi
collection PubMed
description BACKGROUND: Double-strand breakage of chromosomal DNA is obviously a serious threat to cells because various activities of the chromosome depend on its integrity. However, recent experiments suggest that such breakage may occur frequently during "normal" growth in various organisms – from bacteria through vertebrates, possibly through arrest of a replication fork at some endogenous DNA damage. RESULTS: In order to learn how the recombination processes contribute to generation and processing of the breakage, large (> 2000 kb) linear forms of Escherichia coli chromosome were detected by pulsed-field gel electrophoresis in various recombination-defective mutants. The mutants were analyzed in a rich medium, in which the wild-type strain showed fewer of these huge broken chromosomes than in a synthetic medium, and the following results were obtained: (i) Several recB and recC null mutants (in an otherwise rec(+ )background) accumulated these huge linear forms, but several non-null recBCD mutants (recD, recC1001, recC1002, recC1003, recC1004, recC2145, recB2154, and recB2155) did not. (ii) In a recBC sbcA background, in which RecE-mediated recombination is active, recA, recJ, recQ, recE, recT, recF, recO, and recR mutations led to their accumulation. The recJ mutant accumulated many linear forms, but this effect was suppressed by a recQ mutation. (iii) The recA, recJ, recQ, recF and recR mutations led to their accumulation in a recBC sbcBC background. The recJ mutation showed the largest amount of these forms. (iv) No accumulation was detected in mutants affecting resolution of Holliday intermediates, recG, ruvAB and ruvC, in any of these backgrounds. CONCLUSION: These results are discussed in terms of stepwise processing of chromosomal double-strand breaks.
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spelling pubmed-1566512003-06-09 Accumulation of large non-circular forms of the chromosome in recombination-defective mutants of Escherichia coli Handa, Naofumi Kobayashi, Ichizo BMC Mol Biol Research Article BACKGROUND: Double-strand breakage of chromosomal DNA is obviously a serious threat to cells because various activities of the chromosome depend on its integrity. However, recent experiments suggest that such breakage may occur frequently during "normal" growth in various organisms – from bacteria through vertebrates, possibly through arrest of a replication fork at some endogenous DNA damage. RESULTS: In order to learn how the recombination processes contribute to generation and processing of the breakage, large (> 2000 kb) linear forms of Escherichia coli chromosome were detected by pulsed-field gel electrophoresis in various recombination-defective mutants. The mutants were analyzed in a rich medium, in which the wild-type strain showed fewer of these huge broken chromosomes than in a synthetic medium, and the following results were obtained: (i) Several recB and recC null mutants (in an otherwise rec(+ )background) accumulated these huge linear forms, but several non-null recBCD mutants (recD, recC1001, recC1002, recC1003, recC1004, recC2145, recB2154, and recB2155) did not. (ii) In a recBC sbcA background, in which RecE-mediated recombination is active, recA, recJ, recQ, recE, recT, recF, recO, and recR mutations led to their accumulation. The recJ mutant accumulated many linear forms, but this effect was suppressed by a recQ mutation. (iii) The recA, recJ, recQ, recF and recR mutations led to their accumulation in a recBC sbcBC background. The recJ mutation showed the largest amount of these forms. (iv) No accumulation was detected in mutants affecting resolution of Holliday intermediates, recG, ruvAB and ruvC, in any of these backgrounds. CONCLUSION: These results are discussed in terms of stepwise processing of chromosomal double-strand breaks. BioMed Central 2003-04-28 /pmc/articles/PMC156651/ /pubmed/12718760 http://dx.doi.org/10.1186/1471-2199-4-5 Text en Copyright © 2003 Handa and Kobayashi; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.
spellingShingle Research Article
Handa, Naofumi
Kobayashi, Ichizo
Accumulation of large non-circular forms of the chromosome in recombination-defective mutants of Escherichia coli
title Accumulation of large non-circular forms of the chromosome in recombination-defective mutants of Escherichia coli
title_full Accumulation of large non-circular forms of the chromosome in recombination-defective mutants of Escherichia coli
title_fullStr Accumulation of large non-circular forms of the chromosome in recombination-defective mutants of Escherichia coli
title_full_unstemmed Accumulation of large non-circular forms of the chromosome in recombination-defective mutants of Escherichia coli
title_short Accumulation of large non-circular forms of the chromosome in recombination-defective mutants of Escherichia coli
title_sort accumulation of large non-circular forms of the chromosome in recombination-defective mutants of escherichia coli
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC156651/
https://www.ncbi.nlm.nih.gov/pubmed/12718760
http://dx.doi.org/10.1186/1471-2199-4-5
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