1. Antagonistic control of the turnover pathway for the global regulatory sRNA CsrB by the CsrA and CsrD proteins
- Author
-
Yuanyuan Leng, Kazushi Suzuki, Christopher A. Vakulskas, Paul Babitzke, Tony Romeo, Hazuki Abe, Takumi Amaki, and Akihiro Okayama
- Subjects
0301 basic medicine ,RNase P ,RNA Stability ,Protein domain ,Biology ,03 medical and health sciences ,Endoribonucleases ,Escherichia coli ,Genetics ,Binding site ,Terminator Regions, Genetic ,Regulation of gene expression ,Messenger RNA ,Binding Sites ,Base Sequence ,Escherichia coli Proteins ,Membrane Proteins ,RNA-Binding Proteins ,RNA ,Gene Expression Regulation, Bacterial ,Repressor Proteins ,RNA, Bacterial ,030104 developmental biology ,Terminator (genetics) ,Biochemistry ,Mutation ,Transfer RNA ,RNA, Long Noncoding - Abstract
The widely conserved protein CsrA (carbon storage regulator A) globally regulates bacterial gene expression at the post-transcriptional level. In many species, CsrA activity is governed by untranslated sRNAs, CsrB and CsrC in Escherichia coli, which bind to multiple CsrA dimers, sequestering them from lower affinity mRNA targets. Both the synthesis and turnover of CsrB/C are regulated. Their turnover requires the housekeeping endonuclease RNase E and is activated by the presence of a preferred carbon source via the binding of EIIA(Glc) of the glucose transport system to the GGDEF-EAL domain protein CsrD. We demonstrate that the CsrB 3' segment contains the features necessary for CsrD-mediated decay. RNase E cleavage in an unstructured segment located immediately upstream from the intrinsic terminator is necessary for subsequent degradation to occur. CsrA stabilizes CsrB against RNase E cleavage by binding to two canonical sites adjacent to the necessary cleavage site, while CsrD acts by overcoming CsrA-mediated protection. Our genetic, biochemical and structural studies establish a molecular framework for sRNA turnover by the CsrD-RNase E pathway. We propose that CsrD evolution was driven by the selective advantage of decoupling Csr sRNA decay from CsrA binding, connecting it instead to the availability of a preferred carbon source.
- Published
- 2016