1Department of Biochemistry, Okayama University Dental School, 2-5-1 Shikata-cho, Okayama City 700 Japan
2Department of Pharmacology, Kawasaki Medical School, 577 Matsushima, Kurashiki City 701-01, Japan
Tóm tắt
The nucleotide sequence of the Escherichia coli narK gene, which is located in the upstream region of the narCHJI operon, was determined. The narK gene encodes a very hydrophobic protein with 463 amino acid residues (Mr 49 693). A narK deletion mutant, under conditions for the induction of nitrate respiration, was unable to perform nitrate transport. Loss of transport activity was recovered by transforming the mutant with a narK+ plasmid. Thus, we conclude that the narK gene encodes a transmembrane protein participating in nitrate transport. In the narK promoter region, we defined a unique sequence that we designate as a ‘nitrate box’, functioning as a putative NarL‐binding site, in addition to the consensus sequence of the ‘anaero‐box’.
