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. 1999 May;181(9):2802-6.
doi: 10.1128/JB.181.9.2802-2806.1999.

The periplasmic nitrate reductase in Pseudomonas sp. strain G-179 catalyzes the first step of denitrification

L Bedzyk  1 , T Wang, R W Ye
Affiliations

The periplasmic nitrate reductase in Pseudomonas sp. strain G-179 catalyzes the first step of denitrification

L Bedzyk et al. J Bacteriol. 1999 May.

Abstract

Both membrane-bound and periplasmic nitrate reductases have been found in denitrifying bacteria. Yet the role of periplasmic nitrate reductase in denitrification has not been clearly defined. To analyze the function of the periplasmic nitrate reductase in Pseudomonas sp. strain G-179, the nap gene cluster was identified and found to be linked to genes involved in reduction of nitrite and nitric oxide and anaerobic heme biosynthesis. Mutation in the nap region rendered the cells incapable of growing under anaerobic conditions with nitrate as the alternative electron acceptor. No nitrate reduction activity was detected in the Nap- mutant, but that activity could be restored by complementation with the nap region. Unlike the membrane-bound nitrate reductase, the nitrate reduction activity in strain G-179 was not inhibited by a low concentration of azide. Nor could it use NADH as the electron donor to reduce nitrate or use chlorate as the alternative substrate. These results suggest that the periplasmic nitrate reductase in this strain plays a primary role in dissimilatory nitrate reduction.

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Figures

FIG. 1
FIG. 1
Organization of the gene clusters involved in reduction of nitrate, nitrite, and nitric oxide. K, KpnI; B, BamHI; Bg, BglII; H, HindIII; S, SalI.
FIG. 2
FIG. 2
Detection of nitrate reductase from anaerobic cultures. (A) Native gel. Lane 1, wild-type periplasmic fraction; lane 2, TW01 soluble fraction; lane 3, wild-type membrane fraction; lane 4, TW01 membrane fraction. All lanes contained 80 μg of protein. (B) Western blot analysis using polyclonal antibody against the NapA protein. Lane 1, molecular size standard; lane 2, wild-type periplasmic proteins; lane 3, wild-type membrane proteins; lane 4, mutant TW01 total soluble proteins; lane 5, mutant TW01 total membrane proteins.
FIG. 3
FIG. 3
Phylogenetic analysis of Pseudomonas sp. strain G-179. The phylogenetic tree was obtained by the clustal method with DNASTAR software.
See this image and copyright information in PMC

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