Accumulation of sigmaS due to enhanced synthesis and decreased degradation in acidic phospholipid-deficient Escherichia coli cells.
The Escherichia coli pgsA3 mutation, which causes deficiency in acidic phospholipids, leads to a significant accumulation of sigma(S). This accumulation is partly accounted for by the higher transcription level of rpoS; however, it has also been suggested that the cells accumulate sigma(S) post-transcriptionally. We found that the level of the small regulatory RNA RprA, which is involved in the promotion of rpoS translation, is higher in pgsA3 cells than in pgsA(+) cells. Induction of altered rpoS mRNA that does not depend on RprA in pgsA(+) cells did not increase the level of sigma(S) to the high level observed in pgsA3 cells, suggesting post-translational sigma(S) accumulation in the latter. The mRNA levels of clpX and clpP, whose products form a ClpXP protease that degrades sigma(S), were much reduced in pgsA3 cells. Consistent with the reduced mRNA levels, the half-life of sigma(S) in pgsA3 cells was much longer than in pgsA(+) cells, indicating that downregulation of the degradation is a major cause for the high sigma(S) content. We show that the downregulation can be partially attributed to activated CpxAR in the mutant cells, which causes repression of rpoE on whose gene product the expression of clpPX depends.
Uchiyama
Junji
J
Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, Saitama, Japan.
Sasaki
Yu
Y
Nagahama
Hideki
H
Itou
Aya
A
Matsuoka
Satoshi
S
Matsumoto
Kouji
K
Hara
Hiroshi
H
D000074183:ATPases Associated with Diverse Cellular Activities; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D049071:Endopeptidase Clp / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006207:Half-Life; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010743:Phospholipids / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D017855:Transferases (Other Substituted Phosphate Groups) / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; D010743:Phospholipids; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D011494:Protein Kinases; C490475:CpxA protein, E coli; D017855:Transferases (Other Substituted Phosphate Groups); C020676:CDP-diacylglycerol-glycerol-3-phosphate 3-phosphatidyltransferase; D049071:Endopeptidase Clp; D000251:Adenosine Triphosphatases; C088072:ClpX protein, E coli; D000074183:ATPases Associated with Diverse Cellular Activities