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Molecular basis of messenger RNA recognition by the specific bacterial repressing clamp RsmA/CsrA.

Research paper by Mario M Schubert, Karine K Lapouge, Olivier O Duss, Florian C FC Oberstrass, Ilian I Jelesarov, Dieter D Haas, Frédéric H-T FH Allain

Indexed on: 21 Aug '07Published on: 21 Aug '07Published in: Nature Structural and Molecular Biology



Abstract

Proteins of the RsmA/CsrA family are global translational regulators in many bacterial species. We have determined the solution structure of a complex formed between the RsmE protein, a member of this family from Pseudomonas fluorescens, and a target RNA encompassing the ribosome-binding site of the hcnA gene. The RsmE homodimer with its two RNA-binding sites makes optimal contact with an 5'-A/UCANGGANGU/A-3' sequence in the mRNA. When tightly gripped by RsmE, the ANGGAN core folds into a loop, favoring the formation of a 3-base-pair stem by flanking nucleotides. We validated these findings by in vivo and in vitro mutational analyses. The structure of the complex explains well how, by sequestering the Shine-Dalgarno sequence, the RsmA/CsrA proteins repress translation.