Chromatic adaptation in a mutant of Fremyella diplosiphon incapable of phycoerythrin synthesis.

A mutant of the chromatically adapting cyanobacterium Fremyella diplosiphon, incapable of phycoerythrin synthesis but responding to wavelength modulation of its biliprotein content, was isolated. The biliprotein composition of the mutant and of the wild type were identical after growth in red light, but green light induced, in the mutant, the synthesis of a biliviolin-type chromophore bound to some of the alpha subunits of its phycocyanin. Implications of the results on the regulation and possible pathways of biliprotein biosynthesis are discussed.