Characterization of the structural genes for the DNA-binding protein H-NS in Enterobacteriaceae

The promoter region of Escherichia coli hns, the structural gene for the DNA-binding protein H-NS, has been identified by use of a promoter search vector and the in vivo transcriptional start point by primer extension analysis. The homologous hns genes of two other Enterobacteriaceae, Proteus vulgaris and Serratia marcescens, were identified by heterologous hybridization with a DNA probe derived from E. coli hns, cloned and sequenced. Taking into account only the invariant nucleotides and amino acids, the homology of H-NS among the three organisms was found to be greater than 70% at the DNA level and greater than 75% at the protein level. The three hns genes were also found to have nearly identical transcriptional and translational signals.