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- Title
Sok antisense RNA from plasmid R1 is functionally inactivated by RNase E and polyadenylated by poly(A) polymerase I.
- Authors
Mikkelsen, Nikolaj Dam; Gerdes, Kenn
- Abstract
The <em>hok/sok</em> system of plasmid R1, which mediates plasmid stabilization by the killing of plasmid-free cells, codes for two RNA species, Sok antisense RNA and <em>hok</em> mRNA. Sok RNA, which is unstable, inhibits translation of the stable <em>hok</em> mRNA. The 64 nt Sok RNA folds into a single stem-loop domain with an 11 nt unstructured 5′ domain. The initial recognition reaction between Sok RNA and <em>hok</em> mRNA takes place between the 5′ domain and the complementary region in <em>hok</em> mRNA. In this communication we examine the metabolism of Sok antisense RNA. We find that RNase E cleaves the RNA 6nt from its 5′ end and that this cleavage initiates Sok RNA decay. The RNase E cleavage occurs in the part of Sok RNA that is responsible for the initial recognition of the target loop in <em>hok</em> mRNA and thus leads to functional inactivation of the antisense. The major RNase E cleavage product (denoted pSok-6) is rapidly degraded by polynucleotide phosphorylase (PNPase). Thus, the RNase E cleavage tags pSok-6 for further rapid degradation by PNPase from its 3′ end. We also show that Sok RNA is polyadenliated by poly(A) polymerase I (PAP I), and that the poly(A)-tailing is prerequisite for the rapid 3-exonucleolytic degradation by PNPase.
- Publication
Molecular Microbiology, 1997, Vol 26, Issue 2, p311
- ISSN
0950-382X
- Publication type
Academic Journal
- DOI
10.1046/j.1365-2958.1997.5751936.x