The narK gene product participates in nitrate transport induced in Escherichia coli nitrate-respiring cells |
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Authors: | S Noji T Nohno T Saito S Taniguchi |
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Institution: | Department of Biochemistry, Okayama University Dental School, Japan. |
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Abstract: | 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'. |
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