Control of replication of the Lactobacillus pentosus plasmid p353-2: evidence for a mechanism involving transcriptional attenuation of the gene coding for the replication protein.
The synthesis of plasmid DNA and of RNA encoded by the replication protein gene (rep) of plasmid p353-2 of Lactobacillus pentosus was studied for the wild-type plasmid and for a mutant plasmid with a deletion in the 5' untranslated region of the rep gene. Plasmid p353-2 codes for two countertranscript RNAs (CT-RNA) of approximately 75 and 250 nucleotides transcribed from the 5' untranslated region of the rep gene, in opposite directions. In a mutant plasmid with a deletion of the promoter and part of the CT-RNA-encoding sequence which shows a 5- to 10-fold increase in copy number compared to the wild-type plasmid, no CT-RNA could be detected. In the wild-type plasmid more than 90% of transcription initiated at a promoter upstream of the rep gene is prematurely terminated to form a 190 nucleotide truncated RNA, whereas in the mutant plasmid nearly all transcripts reach a size (1100 nucleotides) corresponding to that of the rep gene. A model is presented for the role of CT-RNA in control of plasmid replication, similar to that previously presented for the staphylococcal plasmid pT181, involving a mechanism of transcriptional attenuation of rep RNA at a site just upstream of the rep gene.
Pouwels
P H
PH
TNO Medical Biological Laboratory, Department of Molecular Genetics and Gene-technology, Rijswijk, The Netherlands.
van Luijk
N
N
Leer
R J
RJ
Posno
M
M
D001483:Base Sequence; D015152:Blotting, Northern; D004261:DNA Replication; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D007778:Lactobacillus / Q000235:genetics*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D011401:Promoter Regions, Genetic; D016372:RNA, Antisense; D012329:RNA, Bacterial; D017384:Sequence Deletion
D016372:RNA, Antisense; D012329:RNA, Bacterial