TY - JOUR
T1 - Identical, independent, and opposing roles of ppGpp and DksA in Escherichia coli
AU - Magnusson, Lisa U.
AU - Gummesson, Bertil
AU - Joksimović, Predrag
AU - Farewell, Anne
AU - Nyström, Thomas
PY - 2007/7/1
Y1 - 2007/7/1
N2 - The recent discovery that the protein DksA acts as a coregulator of genes controlled by ppGpp led us to investigate the similarities and differences between the relaxed phenotype of a ppGpp-deficient mutant and the phenotype of a strain lacking DksA. We demonstrate that the absence of DksA and ppGpp has similar effects on many of the observed phenotypes but that DksA and ppGpp also have independent and sometimes opposing roles in the cell. Specifically, we show that overexpression of DksA can compensate for the loss of ppGpp with respect to transcription of the promoters PuspA, PlivJ, and P rrnBP1 as well as amino acid auxotrophy, cell-cell aggregation, motility, filamentation, and stationary phase morphology, suggesting that DksA can function without ppGpp in regulating gene expression. In addition, ppGpp and DksA have opposing effects on adhesion. In the course of our analysis, we also discovered new features of the relaxed mutant, namely, defects in cell-cell aggregation and motility.
AB - The recent discovery that the protein DksA acts as a coregulator of genes controlled by ppGpp led us to investigate the similarities and differences between the relaxed phenotype of a ppGpp-deficient mutant and the phenotype of a strain lacking DksA. We demonstrate that the absence of DksA and ppGpp has similar effects on many of the observed phenotypes but that DksA and ppGpp also have independent and sometimes opposing roles in the cell. Specifically, we show that overexpression of DksA can compensate for the loss of ppGpp with respect to transcription of the promoters PuspA, PlivJ, and P rrnBP1 as well as amino acid auxotrophy, cell-cell aggregation, motility, filamentation, and stationary phase morphology, suggesting that DksA can function without ppGpp in regulating gene expression. In addition, ppGpp and DksA have opposing effects on adhesion. In the course of our analysis, we also discovered new features of the relaxed mutant, namely, defects in cell-cell aggregation and motility.
UR - http://www.scopus.com/inward/record.url?scp=34447540221&partnerID=8YFLogxK
U2 - 10.1128/JB.00330-07
DO - 10.1128/JB.00330-07
M3 - Journal article
C2 - 17496080
AN - SCOPUS:34447540221
SN - 0021-9193
VL - 189
SP - 5193
EP - 5202
JO - Journal of Bacteriology
JF - Journal of Bacteriology
IS - 14
ER -