1.9.6.1	additional information	NapD is a small cytoplasmic protein that is essential for the activity of the periplasmic nitrate reductase and binds tightly to the twinarginine signal peptide of NapA. NapA is structured in its unbound form. The NapA signal peptide undergoes conformational rearrangement upon interaction with NapD. NapA is at least partially folded when bound by its NapD partner. The NapD chaperone binds primarily at the NapA signal peptide in this system and points towards a role for NapD in the insertion of the molybdenum cofactor	742486	
1.9.6.1	physiological function	Escherichia coli is a Gram-negative bacterium that can use nitrate during anaerobic respiration. The catalytic subunit of the involved periplasmic nitrate reductase NapA contains two types of redox cofactor and is exported across the cytoplasmic membrane by the twin-arginine protein transport pathway	742486	
1.9.6.1	malfunction	Salmonella enterica serovar Typhimurium strains with defects in either nitrate reductase A (narG mutant) or the regulator inducing its transcription in the presence of high concentrations of nitrate (narL mutant) exhibit growth comparable to that of wild-type Salmonella enterica serovar Typhimurium. In contrast, a strain lacking a functional periplasmic nitrate reductase (napA mutant) exhibits a marked growth defect in the lumen of the colon. Inactivation of narP, encoding a response regulator that activates napABC transcription in response to low nitrate concentrations, significantly reduces the growth of Salmonella enterica serovar Typhimurium in the murine host gut lumen	-, 742645	
1.9.6.1	additional information	the Salmonella enterica serovar Typhimurium genome contains three nitrate reductases, encoded by the narGHI, narZYV, and napABC genes	-, 742645	
1.9.6.1	physiological function	Salmonella enterica serovar Typhimurium uses the periplasmic nitrate reductase to support its growth on the low nitrate concentrations encountered in the gut, a strategy that may be shared with other enteric pathogens	-, 742645	
1.9.6.1	evolution	the periplasmic nitrate reductase (Nap) from Desulfovibrio desulfuricans belongs to the DMSO reductase family, subfamily I. Classification of Mo-pyranopterin dependent enzymes from the DMSO reductase family, e.g. periplasmic nitrate reductase and formate dehydrogenase, overview. Comparison of the sulfur-shift mechanism in nitrate reductase (Nap) and in formate dehydrogenase (Fdh), detailed overview	742648	
1.9.6.1	physiological function	a mutant strain defective for napA is not able to denitrify and grow on nitrate. The wild-type strain reaches 40 000 ppm of N2O emission and its growth is 10fold higher than that of the mutant strain. In the presence of nitrite as terminal electron acceptor, both wild-type and mutant are able to denitrify and to grow with no significant difference between both strains. NapA plays a role in Agrobacterium fabrum C58 fitness but is not involved in A. fabrum C58 root colonization	-, 764679	
1.9.6.1	physiological function	the anaerobic reduction of NO3- to N2O is lower in Bradyrhizobium japonicum than in Bradyrhizobium diazoefficiens due to impaired periplasmic nitrate reductase (Nap) activity in B. japonicum. Impaired Nap activity in B. japonicum is due to low Nap protein levels	-, 765355