title: A transcription terminator signal necessary for plasmid ColIb-P9 replication.
abstract: Replication of the IncI alpha plasmid ColIb-P9 requires the repZ gene, which encodes an essential, unstable initiator protein termed RepZ. Although many functional features of the ColIb-P9 replicon resemble those of structurally unrelated IncFII plasmids R1 and NR1, the role of transcription of repZ towards the replication origin is poorly understood. Using a series of deletion and substitution mutants of the ColIb-P9 replicon, we found that RepZ prefers to act in cis and that a spacer sequence between repZ and the origin is required for replication. This spacer element, referred to as CIS, retained strong transcription terminator activity. Efficient transcription terminators, whether Rho-dependent or -independent, were capable of replacing CIS function for in vivo replication; ColIb-P9 replicated better as transcription terminated more efficiently within CIS. When the CIS element was substituted for by a strong Rho-dependent terminator, such as lambda tR1 or E. coli trp t', in vivo replication of these recombinant replicons became dependent on the Rho factor, in contrast to the authentic ColIb-P9 replicon.
mesh_terms: D001426:Bacterial Proteins / Q000502:physiology*; D003086:Bacteriocin Plasmids / Q000235:genetics*; D010582:Bacteriophage lambda / Q000235:genetics; D001483:Base Sequence; D004265:DNA Helicases; D004261:DNA Replication / Q000235:genetics*; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010448:Peptide Initiation Factors / Q000502:physiology*; D012329:RNA, Bacterial / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D018741:Replication Origin / Q000235:genetics; D012093:Replicon / Q000235:genetics; D012234:Rho Factor / Q000502:physiology; D017384:Sequence Deletion; D013728:Terminator Regions, Genetic / Q000235:genetics*; D015534:Trans-Activators / Q000502:physiology*; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D010448:Peptide Initiation Factors; D012329:RNA, Bacterial; D012333:RNA, Messenger; D012234:Rho Factor; D015534:Trans-Activators; C045264:replication initiator protein; D004265:DNA Helicases