The rate of processing and degradation of antisense RNAI regulates the replication of ColE1-type plasmids in vivo. |
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Authors: | S Lin-Chao S N Cohen |
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Institution: | Institute of Molecular Biology, Academia Sinica, Nankang Taipei, Taiwan, Republic of China. |
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Abstract: | We show that the rate of degradation of RNAI, an anti-sense repressor of the replication primer RNAII, is a key element of control in the replication of ColE1-type plasmids in vivo. Cleavage of RNAI by RNAase E, a ribosomal RNA-processing enzyme encoded or controlled by the rne (also known as ams) locus, relieves repression by endonucleolytically converting RNAI to a very rapidly decaying product, pRNAI-5. A 5' triphosphate-terminated homolog of pRNAI-5 is degraded slowly and consequently inhibits replication. Nucleotide substitutions within the RNAase E cleavage sequence alter RNAI half-life and plasmid copy number, changing also the incompatibility phenotype. RNAI variants lacking the sequence cleaved by RNAase E are eliminated by growth rate-dependent degradation, resulting in growth-responsive control of plasmid replication and copy number. |
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