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

• Published in: Molecular & general genetics Vol. 242; no. 5; p. 614
• Main Authors: Pouwels, P H, van Luijk, N, Leer, R J, Posno, M
• Format: Journal Article
• Language: English
• Published: Germany 01.03.1994
• Subjects: Base Sequence; Blotting, Northern; DNA Replication; Gene Expression Regulation, Bacterial; Genes, Bacterial; Lactobacillus - genetics; Models, Molecular; Molecular Sequence Data; Plasmids - genetics; Promoter Regions, Genetic; RNA, Antisense; RNA, Bacterial; Sequence Deletion
• ISSN: 0026-8925; 1432-1874
• DOI: 10.1007/BF00285285

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.