The nitrite reductase gene of Pseudomonas aeruginosa: effect of growth conditions on the expression and construction of a mutant by gene disruption.

The expression of nitrite reductase has been tested in a wild-type strain of Pseudomonas aeruginosa (Pao1) as a function of nitrate concentration under anaerobic and aerobic conditions. Very low levels of basal expression are shown under non-denitrifying conditions (i.e. absence of nitrate, in both aerobic and anaerobic conditions); anaerobiosis is not required for high levels of enzyme production in the presence of nitrate. A Pseudomonas aeruginosa strain, mutated in the nitrite reductase gene, has been obtained by gene replacement. This mutant, the first of this species described up to now, is unable to grow under anaerobic conditions in the presence of nitrate. The anaerobic growth can be restored by complementation with the wild-type gene

Pseudomonas aeruginosa nitrite reductase (or cytochrome oxidase): an overview.

The biochemistry and molecular biology of nitrite reductase, a key enzyme in the dissimilatory denitrification pathway of Ps aeruginosa which reduces nitrite to NO, is reviewed in this paper. The enzyme is a non-covalent homodimer, each subunit containing one heme c and one heme d(1). The reaction mechanisms of nitrite and oxygen reduction are discussed in detail, as well as the interaction of the enzyme with its macromolecular substrates, azurin and cytochrome c(551). Special attention is paid to new structural information, such as the chemistry of the d(1) prosthetic group and the primary sequence of the gene and the protein. Finally, results on the expression both in Ps aeruginosa and in heterologous systems are presented