Polyadenylation can regulate ColE1 type plasmid copy number independently of any effect on RNAI decay by decreasing the interaction of antisense RNAI with its RNAII target

• Published in: Plasmid 2002-07, Vol.48 (1), p.49-58
• Main Authors: Xu, Feng-Feng, Gaggero, Carina, Cohen, Stanley N.
• Format: Article
• Language: English
• Subjects: Antisense RNA; Bacterial Proteins - genetics; Base Sequence; Copy number control; DNA Primers; Escherichia coli - genetics; Gene Expression Regulation, Bacterial; Molecular Sequence Data; Nucleic Acid Conformation; pcnB; Plasmid DNA replication; Plasmids - genetics; Poly A - genetics; Poly(A) tails; Polyadenylation; Polymerase Chain Reaction; RNA, Antisense - genetics; RNA, Antisense - metabolism; RNA, Bacterial - genetics; RNA, Small Interfering; RNAI; RNAII
• ISSN: 0147-619X; 1095-9890
• DOI: 10.1016/S0147-619X(02)00023-9

Replication of ColE1-type plasmids is regulated by RNAI, an antisense RNA that interacts with the replication pre-primer, RNAII. Exonucleolytic attack at the 3 ′ end of RNAI is impeded in pcnB mutant bacteria, which lack poly(A) polymerase I—the principal RNA polyadenylase of E. coli; this leads to accumulation of an RNAI decay intermediate (RNAI −5) and dramatic reduction of the plasmid copy number. Here, we report that polyadenylation can also affect RNAI-mediated control of plasmid DNA replication by inhibiting interaction of RNAI −5 with RNAII. We show that mutation of the host pcnB gene profoundly affects the plasmid copy number, even under experimental conditions that limit the effects of polyadenylation on RNAI −5 decay. Moreover, poly(A) tails interfere with RNAI/RNAII interaction in vitro without producing any detectable alteration of RNAI secondary structure. Our results establish the existence of a previously undetected mechanism by which RNA polyadenylation can control plasmid copy number.