Cotranscription of the Escherichia coli isoleucyl-tRNA synthetase (ileS) and prolipoprotein signal peptidase (lsp) genes. Fine-structure mapping of the lsp internal promoter.
We have applied the technique of Northern blotting hybridization analysis to examine the transcription of the Escherichia coli isoleucyl-tRNA synthetase (ileS) and prolipoprotein signal peptidase (lsp) genes. RNA samples from the wild-type strain CS412 and CS412 containing the plasmids pMT521 and pSYC890 were examined with ileS- and lsp-specific 32P-labeled probes. pMT521 is a pBR322 derivative into which a chromosomal DNA fragment containing the ileS and lsp genes has been cloned downstream of the pBR322 tet promoter. pSYC890 is a derivative of pMT521 which lacks the tet promoter, but nevertheless is active in lsp mRNA transcription due to the presence of a weak lsp internal promoter located in the distal portion of the upstream ileS DNA, RNA from CS412(pMT521) exhibited a high level of a 5500-nucleotide ileS-lsp cotranscript that hybridized to both probes. RNA from CS412(pSYC890) contained a high level of low molecular weight lsp-specific transcripts from the lsp internal promoter. However, only high molecular weight (5000-6500 nucleotides) cotranscripts were detected in RNA from CS412 by Northern blotting analysis. A trace level of lsp-specific mRNA was detected in CS412 by S1 nuclease mapping. The 5'-end of this transcript was mapped using RNA from CS412(pSYC890). The mRNA begins 192/193 base pairs upstream of the lsp translation initiation codon at a site within ileS DNA that codes for the aspartate residue located 61 amino acids from the carboxyl-terminal of ILES. In conclusion, most of the transcription of lsp in wild-type E. coli originates from upstream of ileS and yields ileS-lsp cotranscripts.
D000604:Amino Acyl-tRNA Synthetases / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics; D004274:DNA, Recombinant; D010450:Endopeptidases / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology*; D005798:Genes, Bacterial; D007533:Isoleucine-tRNA Ligase / Q000235:genetics*; D008565:Membrane Proteins; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012697:Serine Endopeptidases; D014158:Transcription, Genetic
D004269:DNA, Bacterial; D004274:DNA, Recombinant; D008565:Membrane Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D010450:Endopeptidases; D012697:Serine Endopeptidases; C026515:type I signal peptidase; D000604:Amino Acyl-tRNA Synthetases; D007533:Isoleucine-tRNA Ligase