Photocontrol of Phycoerythrocyanin Synthesis in an Oscillatoria Strain (Cyanobacteria)

Abstract

In Cyanobacteria, pigment synthesis can be affected by physical and chemical factors of the environment (Cohen-Bazire, Bryant, 1982). The phycobiliproteins (PBP) aggregated in phycobilisomes (PBS) act as light-harvesting complexes the absorbed energy being very efficiently funnelled to chlorophyll a. PBP synthesis can be controlled by light intensity, but the most striking effect of light is the modulation of PBP synthesis by light quality. This promotes a complementary chromatic adaptation phycoerythrin (PE) synthesis favoured by green light and phycocyanin (PC) by red light (Bogorad, 1975 ; Tandeau de Marsac (1977). The third main PBP, allophycyanin (APC) does not seem to be controlled in such a way (Glazer, 1982). Recently, a new PBP, phycoerythrocyanin (PEC) with an absorption maximum at 568 nm has been isolated and characterized from several heterocystous strains of Cyanobacteria (Bryant et al., 1976 ; Nies, Wehrmeyer, 1980 ; Fuglistaller et al., 1981). One may ask if PEC functionnally equivalent to PE, could be submitted to complementary chromatic adaptation. This ability was reported for Mastigocladus laminosus in open air cultures (Fuglistaller et al., 1981) while Bryant (1982) failed to detect such a phenomenon in 36 strains of the Pasteur Culture Collection in well-defined culture conditions.