Roles of polyadenylation and nucleolytic cleavage in the filamentous phage mRNA processing and decay pathways in Escherichia coli

To define basic features of mRNA processing and decay in Escherichia coli, we have examined a set of mRNAs encoded by the filamentous phage f1 that have structures typical of bacterial mRNAs. They bear a stable hairpin stem-loop on the 3′ end left from rho-independent termination and are known to un...

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Bibliographic Details
Published in:	RNA (Cambridge) Vol. 5; no. 7; pp. 972 - 985
Main Authors:	GOODRICH, A. FRANCES, STEEGE, DEBORAH A.
Format:	Journal Article
Language:	English
Published:	United States Cambridge University Press 01-07-1999
Subjects:	Bacteriophages - genetics Base Sequence Cell Nucleolus - metabolism Endoribonucleases - metabolism Escherichia coli Escherichia coli - enzymology Escherichia coli - metabolism Escherichia coli Proteins Molecular Sequence Data mRNA decay Phage f1 Poly A - metabolism poly(A) Polynucleotide Adenylyltransferase - metabolism ribonuclease E Ribonuclease III RNA Processing, Post-Transcriptional RNA, Messenger - metabolism RNA, Viral - metabolism RNase E RNase E cleavage RNA secondary structure 3′ [right arrow] 5′ exonucleolytic mRNA decay
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Summary:	To define basic features of mRNA processing and decay in Escherichia coli, we have examined a set of mRNAs encoded by the filamentous phage f1 that have structures typical of bacterial mRNAs. They bear a stable hairpin stem-loop on the 3′ end left from rho-independent termination and are known to undergo processing by RNase E. A small percentage of the f1 mRNAs were found to bear poly(A) tails that were attached to heterogeneous positions near the common 3′ end. In a poly(A) polymerase-deficient host, the later-appearing processed mRNAs were stabilized, and a novel small RNA accumulated. This ∼125-nt RNA proved to arise via RNase E cleavage from the 3′-terminal region of the mRNAs bearing the terminator. Normally ribosomes translating gene VIII appear to protect this cleavage site from RNase E, so that release of the fragment from the mRNAs occurs very slowly. The data presented define additional steps in the f1 mRNA processing and decay pathways and clarify how features of the pathways are used in establishing and maintaining the persistent filamentous phage infection. Although the primary mode of decay is endonucleolytic cleavage generating a characteristic 5′ [right arrow] 3′ wave of products, polyadenylation is involved in part in degradation of the processed mRNAs and is required for turnover of the 125-nt mRNA fragment. The results place polyadenylation at a later rather than an initiating step of decay. They also provide a clear illustration of how stably structured RNA 3′ ends act as barriers to 3′ [right arrow] 5′ exonucleolytic mRNA decay.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	1355-8382 1469-9001
DOI:	10.1017/S1355838299990398