Involved in the biosynthesis of pyocyanine, a blue-pigmented phenazine derivative, which plays a role in virulence. Catalyzes the oxidative decarboxylation of 5-methylphenazine-1-carboxylate (5-methyl-PCA) to pyocyanine. Can also act on phenazine-1-carboxylate (PCA), converting it into 1-hydroxyphenazine (1-HP). However, PCA is a poor substrate. 5-methyl-phenazine-1-carboxylate + 2 H(+) + NADH + O2 = CO2 + H2O + NAD(+) + pyocyanin Secondary metabolite biosynthesis; pyocyanine biosynthesis. Monomer in solution. Probably interacts transiently with PhzM.