TY - JOUR
T1 - Complex regulation of the global regulatory gene csrA
T2 - CsrA-mediated translational repression, transcription from five promoters by Eσ70 and EσS, and indirect transcriptional activation by CsrA
AU - Yakhnin, Helen
AU - Yakhnin, Alexander V.
AU - Baker, Carol S.
AU - Sineva, Elena
AU - Berezin, Igor
AU - Romeo, Tony
AU - Babitzke, Paul
PY - 2011/8
Y1 - 2011/8
N2 - CsrA of Escherichia coli is an RNA-binding protein that globally regulates gene expression by repressing translation and/or altering the stability of target transcripts. Here we explored mechanisms that control csrA expression. Four CsrA binding sites were predicted upstream of the csrA initiation codon, one of which overlapped its Shine-Dalgarno sequence. Results from gel shift, footprint, toeprint and in vitro translation experiments indicate that CsrA binds to these four sites and represses its own translation by directly competing with 30S ribosomal subunit binding. Experiments were also performed to examine transcription of csrA. Primer extension, in vitro transcription and in vivo expression studies identified two σ70-dependent (P2 and P5) and two σS-dependent (P1 and P3) promoters that drive transcription of csrA. Additional primer extension studies identified a fifth csrA promoter (P4). Transcription from P3, which is indirectly activated by CsrA, is primarily responsible for increased csrA expression as cells transition from exponential to stationary-phase growth. Taken together, our results indicate that regulation of csrA expression occurs by a variety of mechanisms, including transcription from multiple promoters by two sigma factors, indirect activation of its own transcription, as well as direct repression of its own translation.
AB - CsrA of Escherichia coli is an RNA-binding protein that globally regulates gene expression by repressing translation and/or altering the stability of target transcripts. Here we explored mechanisms that control csrA expression. Four CsrA binding sites were predicted upstream of the csrA initiation codon, one of which overlapped its Shine-Dalgarno sequence. Results from gel shift, footprint, toeprint and in vitro translation experiments indicate that CsrA binds to these four sites and represses its own translation by directly competing with 30S ribosomal subunit binding. Experiments were also performed to examine transcription of csrA. Primer extension, in vitro transcription and in vivo expression studies identified two σ70-dependent (P2 and P5) and two σS-dependent (P1 and P3) promoters that drive transcription of csrA. Additional primer extension studies identified a fifth csrA promoter (P4). Transcription from P3, which is indirectly activated by CsrA, is primarily responsible for increased csrA expression as cells transition from exponential to stationary-phase growth. Taken together, our results indicate that regulation of csrA expression occurs by a variety of mechanisms, including transcription from multiple promoters by two sigma factors, indirect activation of its own transcription, as well as direct repression of its own translation.
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U2 - 10.1111/j.1365-2958.2011.07723.x
DO - 10.1111/j.1365-2958.2011.07723.x
M3 - Article
C2 - 21696456
AN - SCOPUS:79960722197
SN - 0950-382X
VL - 81
SP - 689
EP - 704
JO - Molecular Microbiology
JF - Molecular Microbiology
IS - 3
ER -