Genetic Approaches to Study the Interplay Between Transcription and Nucleoid-Associated Proteins in Escherichia coli.

Bacterial nucleoid-associated proteins are important factors in regulation of transcription, in nucleoid structuring, and in homeostasis of DNA supercoiling. Vice versa, transcription influences DNA supercoiling and can affect DNA binding of nucleoid-associated proteins (NAPs) such as H-NS in Escherichia coli. Here we describe genetic tools to study the interplay between transcription and nucleoid-associated proteins in E. coli. These methods include construction of genomic and plasmidic transcriptional and translational lacZ reporter gene fusions to study regulation of promoters; insertion of promoter cassettes to drive transcription into a locus of interest in the genome, for example, an H-NS-bound locus; and construction of isogenic hns and stpA mutants and precautions in doing so.