Nucleotide sequence of the fnr gene and primary structure of the Enr protein of Escherichia coli.

The nucleotide sequence of a 1.64 kb fragment of E. coli DNA containing the fnr gene (regulatory gene for fumarate and nitrate reduction) was determined using the dideoxy chain termination method. The fnr coding region (750 bp) was identified, and the initiation and termination points of fnr transcription were located by RNA:DNA hybridisation with single-stranded M13 probes. The DNA fragment also contained the 5' end of a separately transcribed gene of unknown function. The deduced molecular weight (27947) of the Fnr protein was in agreement with that of the protein identified by the maxicell procedure, and the primary structure contained regions of homology with several transcriptional regulator proteins.