Cleavage of poly(A) tails on the 3′-end of RNA by ribonuclease E of Escherichia coli

AUTOR(ES)

Walsh, A. P.

FONTE

Oxford University Press

RESUMO

RNase E initiates the decay of Escherichia coli RNAs by cutting them internally near their 5′-end and is a component of the RNA degradosome complex, which also contains the 3′-exonuclease PNPase. Recently, RNase E has been shown to be able to remove poly(A) tails by what has been described as an exonucleolytic process that can be blocked by the presence of a phosphate group on the 3′-end of the RNA. We show here, however, that poly(A) tail removal by RNase E is in fact an endonucleolytic process that is regulated by the phosphorylation status at the 5′- but not the 3′-end of RNA. The rate of poly(A) tail removal by RNase E was found to be 30-fold greater when the 5′-terminus of RNA substrates was converted from a triphosphate to monophosphate group. This finding prompted us to re-analyse the contributions of the ribonucleolytic activities within the degradosome to 3′ attack since previous studies had only used substrates that had a triphosphate group on their 5′-end. Our results indicate that RNase E associated with the degradosome may contribute to the removal of poly(A) tails from 5′-monophosphorylated RNAs, but this is only likely to be significant should their attack by PNPase be blocked.

Documentos Relacionados

• 3'-end labeling of RNA with recombinant yeast poly(A) polymerase.
• Host factor Hfq of Escherichia coli stimulates elongation of poly(A) tails by poly(A) polymerase I
• Polyomavirus early region alternative poly(A) site: 3'-end heterogeneity and altered splicing pattern.
• Multiple forms of poly(A) polymerases purified from HeLa cells function in specific mRNA 3'-end formation.
• Different positioning elements select poly(A) sites at the 3'-end of GCN4 mRNA in the yeast Saccharomyces cerevisiae.