Transcriptional Analysis of Essential Genes of the Escherichia coli Fatty Acid Biosynthesis Gene Cluster by Functional Replacement with the Analogous Salmonella typhimurium Gene Cluster

摘要: The genes encoding several key fatty acid biosynthetic enzymes (called the fab cluster) are clustered in order plsX-fabH-fabD-fabG-acpP-fabF at min 24 of Escherichia coli chromosome. A difficulty analysis cluster by polar allele duplication approach (Y. Zhang and J. E. Cronan, Jr., Bacteriol. 178:3614–3620, 1996) is that these essential for growth coli. We overcame this complication use gene Salmonella typhimurium, a close relative coli, to provide functions necessary growth. S. typhimurium was isolated complementation an fabD mutant found encode proteins with >94% homology those However, sequences cannot recombine required direct via homologous recombination. Using approach, we although approximately 60% plsX transcripts initiate promoters located far upstream include rpmF ribosomal protein gene, promoter coding sequence (probably within rpmF) sufficient normal have also fabG obligatorily cotranscribed genes. Insertion transcription terminator cassette (Ω-Cm cassette) between chromosome abolished blocked cell growth, thus providing first indication gene. Ω-Cm fabH caused greatly decreased slower cellular indicating has only weak promoter(s).