Catalyzes the reduction of nitrite to nitric oxide (NO). It could be essential for growth and survival in oxygen-depleted environments. Fe(III)-[cytochrome c] + H2O + nitric oxide = Fe(II)-[cytochrome c] + 2 H(+) + nitrite Binds 1 Cu(+) ion. Binds 1 Cu(2+) ion. Homotrimer. Belongs to the multicopper oxidase family.