A Rhodobacter sphaeroides gene (pps) induces trans suppression of bacteriochlorophyll (Bch) and carotenoid (Crt) levels in both R. sphaeroides and R. R. capsulatus. It also induces suppression of Crt levels in a Paracoccus denitrificans strain carrying the Crt genes of R. sphaeroides. The gene is located approximately 11 kilobases from crtA in the photosynthetic gene cluster. Crt suppression by pps is quantitatively different from that caused by an absence of mature Bch.