Escherichia coli ribonuclease III activity is downregulated by osmotic stress: consequences for the degradation of bdm mRNA in biofilm formation.
During the course of experiments aimed at identifying genes with ribonuclease III (RNase III)-dependent expression in Escherichia coli, we found that steady state levels of bdm mRNA were dependent on cellular concentrations of RNase III. The half-lives of adventitiously overexpressed bdm mRNA and the activities of a transcriptional bdm'-'cat fusion were observed to be dependent on cellular concentrations of RNase III, indicating the existence of cis-acting elements in bdm mRNA responsive to RNase III. In vitro and in vivo cleavage analyses of bdm mRNA identified two RNase III cleavage motifs, one in the 5'-untranslated region and the other in the coding region of bdm mRNA, and indicated that RNase III cleavages in the coding region constitute a rate-determining step for bdm mRNA degradation. We also discovered that downregulation of the ribonucleolytic activity of RNase III is required for the sustained elevation of RcsB-induced bdm mRNA levels during osmotic stress and that cells overexpressing bdm form biofilms more efficiently. These findings indicate that the Rcs signalling system has an additional regulatory pathway that functions to modulate bdm expression and consequently, adapt E. coli cells to osmotic stress.
Sim
Se-Hoon
SH
Department of Life Science (BK21 program), Chung-Ang University, Seoul, Republic of Korea.
Yeom
Ji-Hyun
JH
Shin
Choy
C
Song
Woo-Seok
WS
Shin
Eunkyoung
E
Kim
Hong-Man
HM
Cha
Chang-Jun
CJ
Han
Seung Hyun
SH
Ha
Nam-Chul
NC
Kim
Si Wouk
SW
Hahn
Yoonsoo
Y
Bae
Jeehyeon
J
Lee
Kangseok
K
D001483:Base Sequence; D017931:DNA Primers; D015536:Down-Regulation; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D007700:Kinetics; D009994:Osmolar Concentration; D010957:Plasmids / Q000235:genetics; D020641:Polymorphism, Single Nucleotide; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D043244:Ribonuclease III / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism
D017931:DNA Primers; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; C489568:RcsB protein, E coli; D014157:Transcription Factors; D043244:Ribonuclease III; C468366:ribonuclease III, E coli