Physiological and genetic regulation of rRNA synthesis in Lactococcus.
The macromolecular composition of Lactococcus was regulated by growth rate in the same general way as that of less fastidious bacteria such as Escherichia coli and Salmonella typhimurium. The ratios of RNA:DNA and RNA:protein increased approximately threefold over a 13.5-fold increase in growth rate, whereas the ratio of DNA:protein remained approximately constant. Using reporter genes fused to a DNA fragment of a cloned lactococcal rRNA operon, promoter activity was located upstream of the 16S rRNA structural gene. This DNA fragment had some characteristics typical of a rrn promoter in E. coli. Two consensus promoter sequences P1 and P2 were located 296 and 157 bp, respectively, upstream of the start of the 16S rRNA gene. Between P2 and the start of the 16S rRNA gene, sequences were identified with typical anti-termination motifs characteristic of E. coli rrn promoter regions. A putative transcription terminator sequence was identified downstream of the 5S rRNA gene and putative primary RNA transcript processing sites at both ends of the lactococcal rRNA operon were also noted.
Beresford
T
T
Department of Food Microbiology, University College, Cork, Ireland.
Condon
S
S
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D013294:Lactococcus lactis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D008969:Molecular Sequence Data; D009876:Operon; D011401:Promoter Regions, Genetic; D012323:RNA Processing, Post-Transcriptional; D012329:RNA, Bacterial / Q000096:biosynthesis* / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000096:biosynthesis* / Q000235:genetics
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S