Premium
Dynamic state of DNA topology is essential for genome condensation in bacteria
Author(s) -
Ohniwa Ryosuke L,
Morikawa Kazuya,
Kim Joongbaek,
Ohta Toshiko,
Ishihama Akira,
Wada Chieko,
Takeyasu Kunio
Publication year - 2006
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7601414
Subject(s) - biology , dna , genome , bacteria , genetics , computational biology , topology (electrical circuits) , gene , mathematics , combinatorics
In bacteria, Dps is one of the critical proteins to build up a condensed nucleoid in response to the environmental stresses. In this study, we found that the expression of Dps and the nucleoid condensation was not simply correlated in Escherichia coli , and that Fis, which is an E. coli (gamma‐Proteobacteria)‐specific nucleoid protein, interfered with the Dps‐dependent nucleoid condensation. Atomic force microscopy and Northern blot analyses indicated that the inhibitory effect of Fis was due to the repression of the expression of Topoismerase I (Topo I) and DNA gyrase. In the Δ fis strain, both topA and gyrA/B genes were found to be upregulated. Overexpression of Topo I and DNA gyrase enhanced the nulceoid condensation in the presence of Dps. DNA‐topology assays using the cell extract showed that the extracts from the Δ fis and Topo I‐/DNA gyrase‐overexpressing strains, but not the wild‐type extract, shifted the population toward relaxed forms. These results indicate that the topology of DNA is dynamically transmutable and that the topology control is important for Dps‐induced nucleoid condensation.