Premium
The small RNA, DsrA, is essential for the low temperature expression of RpoS during exponential growth in Escherichia coli.
Author(s) -
Sledjeski D. D.,
Gupta A.,
Gottesman S.
Publication year - 1996
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 - 10.1002/j.1460-2075.1996.tb00773.x
Subject(s) - rpos , biology , sigma factor , gene expression , transcription (linguistics) , genetics , rna , lac operon , gene , microbiology and biotechnology , promoter , linguistics , philosophy
dsrA encodes a small, untranslated RNA. When over‐expressed, DsrA antagonizes the H‐NS‐mediated silencing of numerous promoters. Cells devoid of DsrA grow normally and show little change in the expression of a number of H‐NS‐silenced genes. Expression of a transcriptional fusion of lacZ to dsrB, the gene next to dsrA, is significantly lower in cells carrying mutations in dsrA. All expression of beta‐galactosidase from the dsrB::lacZ fusion is also dependent on the stationary phase sigma factor, RpoS. DsrA RNA was found to regulate dsrB::lacZ indirectly, by modulating RpoS synthesis. Levels of RpoS protein are substantially lower in a dsrA mutant, both in stationary and exponential phase cells. Mutations in dsrA decrease the expression of an RpoS::LacZ translational fusion, but not a transcriptional fusion, suggesting that DsrA is acting after transcription initiation. While RpoS expression is very low in exponential phase at temperatures of 30 degrees C and above, at 20 degrees C there is substantial synthesis of RpoS during exponential growth, all dependent on DsrA RNA. dsrA expression is also increased at low temperatures. These results suggest a new role for RpoS during exponential growth at low temperatures, mediated by DsrA.