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Nucleoid organization in the radioresistant bacterium D einococcus radiodurans
Author(s) -
Passot Fanny Marie,
Nguyen Hong Ha,
DardDascot Cloelia,
Thermes Claude,
Servant Pascale,
Espéli Olivier,
Sommer Suzanne
Publication year - 2015
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.13064
Subject(s) - deinococcus radiodurans , biology , nucleoid , locus (genetics) , radioresistance , genetics , dna , chromosome , microbiology and biotechnology , chromosome segregation , dna repair , escherichia coli , gene , cell culture
Summary Processes favoring the exceptional resistance to genotoxic stress of D einococcus radiodurans are not yet completely characterized. It was postulated that its nucleoid and chromosome(s) organization could participate in the DNA double strand break repair process. Here, we investigated the organization of chromosome 1 by localization of three chromosomal loci including oriC, Ter and a locus located in its left arm. For this purpose, we used a ParB ‐ parS system to visualize the position of the loci before and after exposure to γ‐rays. By comparing the number of fluorescent foci with the number of copies of the studied loci present in the cells measured by quantitative polymerase chain reaction ( qPCR ), we demonstrated that the 4–10 copies of chromosome 1 per cell are dispersed within the nucleoid before irradiation, indicating that the chromosome copies are not prealigned. Chromosome segregation is progressive but not co‐ordinated, allowing each locus to be paired with its sister during part of the cell cycle. After irradiation, the nucleoid organization is modified, involving a transient alignment of the loci in the late stage of DNA repair and a delay of segregation of the Ter locus. We discuss how these events can influence DNA double strand break repair.