The RNA degradosome and poly(A) polymerase of Escherichia coli are required in vivo for the degradation of small mRNA decay intermediates containing REP-stabilizers
Article first published online: 10 DEC 2003
Volume 51, Issue 3, pages 777–790, February 2004
How to Cite
Khemici, V. and Carpousis, A. J. (2004), The RNA degradosome and poly(A) polymerase of Escherichia coli are required in vivo for the degradation of small mRNA decay intermediates containing REP-stabilizers. Molecular Microbiology, 51: 777–790. doi: 10.1046/j.1365-2958.2003.03862.x
- Issue published online: 16 DEC 2003
- Article first published online: 10 DEC 2003
- Accepted 3 October, 2003.
In Escherichia coli, REP-stabilizers are structural elements in polycistronic messages that protect 5′-proximal cistrons from 3′5′ exonucleolytic degradation. The stabilization of a protected cistron can be an important determinant in the level of gene expression. Our results suggest that RNase E, an endoribonuclease, initiates the degradation of REP-stabilized mRNA. However, subsequent degradation of mRNA fragments containing a REP-stabilizer poses a special challenge to the mRNA degradation machinery. Two enzymes, the DEAD-box RNA helicase, RhlB and poly(A) polymerase (PAP) are required to facilitate the degradation of REP-stabilizers by polynucleotide phosphorylase (PNPase). This is the first in vivo evidence that these enzymes are required for the degradation of REP-stabilizers. Furthermore, our results show that REP degradation by RhlB and PNPase requires their association with RNase E as components of the RNA degradosome, thus providing the first in vivo evidence that this ribonucleolytic multienzyme complex is involved in the degradation of structured mRNA fragments.