A novel sRNA component of the carbon storage regulatory system of Escherichia coli.
Small untranslated RNAs (sRNAs) perform a variety of important functions in bacteria. The 245 nucleotide sRNA of Escherichia coli, CsrC, was discovered using a genetic screen for factors that regulate glycogen biosynthesis. CsrC RNA binds multiple copies of CsrA, a protein that post-transcriptionally regulates central carbon flux, biofilm formation and motility in E. coli. CsrC antagonizes the regulatory effects of CsrA, presumably by sequestering this protein. The discovery of CsrC is intriguing, in that a similar sRNA, CsrB, performs essentially the same function. Both sRNAs possess similar imperfect repeat sequences (18 in CsrB, nine in CsrC), primarily localized in the loops of predicted hairpins, which may serve as CsrA binding elements. Transcription of csrC increases as the culture approaches the stationary phase of growth and is indirectly activated by CsrA via the response regulator UvrY. Because CsrB and CsrC antagonize CsrA activity and depend on CsrA for their synthesis, a csrB null mutation causes a modest compensatory increase in CsrC levels and vice versa. Homologues of csrC are apparent in several Enterobacteriaceae. The regulatory and evolutionary implications of these findings are discussed.
Weilbacher
Thomas
T
Department of Molecular Biology and Immunology, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107-2699, USA.
Suzuki
Kazushi
K
Dubey
Ashok K
AK
Wang
Xin
X
Gudapaty
Seshigirao
S
Morozov
Igor
I
Baker
Carol S
CS
Georgellis
Dimitris
D
Babitzke
Paul
P
Romeo
Tony
T
D001483:Base Sequence; D018441:Biofilms; D002244:Carbon / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006003:Glycogen / Q000378:metabolism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D020871:RNA Stability; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism
C093587:CsrA protein, E coli; D029968:Escherichia coli Proteins; D012329:RNA, Bacterial; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D002244:Carbon; D006003:Glycogen