To study the regulation of expression of the Serratia plymuthica gene chiA encoding a 58-kDa endochitinase, its 586-bp-long upstream regulatory region was cloned, sequenced and fused to a promoterless lac operon in phage λRS45 to obtain a single-copy transcriptional fusion (PF1chiA-lac) in lysogens of Escherichia coli wild-type strains or their mutants deficient in various global regulators of transcription. The level of PF1chiA-lac expression increased about 20- and 90-fold, respectively, in E. coli K12 Δhns and double Δhns stpA mutants deficient in H-NS, and in both H-NS and StpA DNA-binding histone-like proteins, as compared to levels in the wild-type strain. In a Δlrp mutant deficient in the leucine-responsive transcriptional regulator Lrp, the level of PF1chiA-lac expression increased only up to threefold, whereas even smaller differences relative to the wild-type strain were observed in rpoS and Δcrp mutants deficient in the σS subunit of RNA polymerase and catabolite-repression protein (CRP), respectively. Deletion of the inverted-repeat sequences and curved DNA regions located in the upstream region of chiA essentially did not influence strain IC1270's chiA promoter activity in E. coli.
ASJC Scopus subject areas
- Applied Microbiology and Biotechnology