Disease relevance of napF

• The nap gene clusters in many bacteria, including Rhodobacter sphaeroides DSM158, contain an napF gene, disruption of which drastically decreases both in vitro and in vivo nitrate reductase activities [1].
• The napF and narG nitrate reductase operons in Escherichia coli are differentially expressed in response to submicromolar concentrations of nitrate but not nitrite [2].

High impact information on napF

• Taking into account the cytoplasmic localization of NapF, the presence of labile Fe-S clusters in the protein, the napF(-) strain phenotype, and the NapF-dependent reactivation of the 2,2'-dipyridyl-treated NapA, we propose a role for NapF in assembling the [4Fe-4S] center of the catalytic subunit NapA [1].
• The finding that IscR repressed expression of the hyaA, hybO and napF promoters specifically under aerobic growth conditions suggests a new mechanism to explain their upregulation under anaerobic growth conditions [3].
• NapF, NapG and NapH were shown to play no role in electron transfer from menaquinol to the NapAB complex but, in the Ubi+Men- background, deletion of napF, napGH or napFGH all resulted in total loss of nitrate-dependent growth [4].
• The R. sphaeroides napF gene product is a 16.4 kDa protein with four cysteine clusters that probably bind four [4Fe-4S] centres [5].
• Previous studies have shown that the napF operon control region directs synthesis of two transcripts whose 5' ends differ by about 3 nucleotides [6].

Biological context of napF

• Utilizing a napF-lacZ operon fusion, we demonstrate that napF gene expression is impaired in strain defective for the molybdate-responsive ModE transcription factor [7].
• The upstream ModE regulatory site functions to override nitrate control of napF gene expression when the essential enzyme component, molybdate, is limiting in the cell environment [7].
• These results establish the unconventional napF operon control region architecture, in which the major promoter P1 is activated by the Fnr protein bound to a site centered at -64.5 with respect to the transcription initiation site, working in conjunction with the phospho-NarP protein bound to a site centered at -44.5 [6].
• The napF operon control region exhibits unusual organization of DNA binding sites for the transcription regulators Fnr and NarP, which activate transcription in response to anaerobiosis and nitrate, respectively [6].
• The transcriptional regulation of napF was successfully reproduced in vitro by using a supercoiled plasmid template and purified Fnr, NarL, and NarP proteins [8].

Associations of napF with chemical compounds

• Finally, nitrate, but not nitrite, was essential for repression of napF gene expression [2].

Other interactions of napF

• In contrast, deletion of the upstream ModE region site rendered napF expression independent of modE [7].

Analytical, diagnostic and therapeutic context of napF

• To address why the cell makes these two enzymes, continuous cell culture techniques were used to examine napF and narG gene expression in response to different concentrations of nitrate and/or nitrite [2].

References