| 1. |
- He, Lin, et al.
(författare)
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PcnB is required for the rapid degradation of RNAI, the antisense RNA that controls the copy number of ColE1-related plasmids
- 1993
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Ingår i: Molecular Microbiology. - : Wiley. - 0950-382X .- 1365-2958. ; 9:6, s. 1131-1142
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Tidskriftsartikel (refereegranskat)abstract
- The replication of ColE1-related plasmids is controlled by an unstable antisense RNA, RNAI, which can interfere with the successful processing of the RNAII primer of replication. We show here that a host protein, PcnB, supports replication by promoting the decay of RNAI. In bacterial strains deleted for PcnB a stable, active form of RNAI, RNAI*, which appears to be identical to the product of 5'-end processing by RNAase E, accumulates. This leads to a reduction in plasmid copy number. We show, using a GST-PcnB fusion protein, that PcnB does not interfere with RNAI/RNAII binding in vitro. The fusion protein, like PcnB, has polyadenylating activity and is able to polyadenylate RNAI (and also another antisense RNA, CopA) in vitro.
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| 2. |
- van Biesen, T, et al.
(författare)
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Structural and functional analyses of the FinP antisense RNA regulatory system of the F conjugative plasmid
- 1993
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Ingår i: Molecular Microbiology. - : Wiley. - 0950-382X .- 1365-2958. ; 10:1, s. 35-43
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of conjugation of F-like plasmids is regulated by the FinOP fertility inhibition system. The transfer (tra) operon is under the direct control of the TraJ transcriptional activator which, in turn, is negatively regulated by FinP, an antisense RNA, and FinO, a 22 kDa protein. Recently, FinO has been shown to extend the chemical stability of FinP in vivo in the absence of traJ mRNA. The in vitro secondary structures of both the FinP and TraJ RNAs were determined by the use of single- and double-strand-specific nucleases; both RNAs were found to have double stem-loop structures that are complementary to each other and, therefore, FinP RNA and TraJ RNA have the potential to form a duplex with each other. This was verified by in vitro binding experiments. The reaction was shown to be biomolecular with an apparent rate constant (kapp) of 5 x 10(5)M-1s-1, a value that is similar to those found for other natural antisense RNA systems. Preliminary evidence for the in vivo formation of the FinP-TraJ RNA duplex was obtained by primer extension of the traJ mRNA; the presence of both FinO and FinP was required to cause a dramatic reduction in the steady-state level of traJ mRNA, perhaps as a result of RNase III degradation of the resulting RNA duplex.
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