Phycobilisomes

Light Intensity Adaptation and Phycobilisome Composition of Microcystis aeruginosa

“…as observed by transmission EM, is primarily hemidiscoidal, although other structural forms have been reported (1, 2,8,10,11,24,28). The central core consists of three discs arranged to form an equilateral triangle in face view.…”

“…The core is surrounded by a hemdiscoidal array of up to six rod-like arms composed of stacks of discs. Biophysical and biochemical evidence suggests that PE hexamers, when present, are equivalent to the outer rod discs and PC hexamers are the rod discs closest to the core which consists of discs of APC trimers (2,7,8,10).…”

“…The light-harvesting systems of cyanobacteria, red algae, and cyanelles are supramolecular aggregates of phycobiliproteins, called phycobilisomes, bound to the external surface ofthylakoid membranes (2,7,8,10,11). Phycobilisomes collect light energy and transfer it with nearly 100% efficiency to the photosynthetic reaction centers, primarily to those of PSII (4,16,17,27).…”

“…All red algae and cyanobacteria contain APC2 and PC. Many have, in addition, PE or other related phycobiliproteins (2,8,11). The PE and PC content is often regulated by chromatic adaptation (24).…”

A molecular understanding of complementary chromatic adaptation

“…Specific lyases catalyze the attachment of the chromophore to the apo-phycobiliprotein (Fairchild et al 1992;Fairchild and Glazer 1994;. A number of investigators have done marvelous work that has helped elucidate the structure and function of PBS; these include Elizabeth Gantt (Gantt 1981), Alex Glazer (Glazer and CohenBazire 1971;Glazer 1982;Glazer et al 1983;Glazer 1985), Herbert Zuber (Glauser et al 1992(Glauser et al , 1993 and Robert Huber (Schirmer et al 1986), and a detailed description of PBS structure can be found in a number of review articles (Gantt 1981;Glazer et al 1983;Glazer 1985;Sidler 1994). Figure 2 shows Alex Glazer (right) along with former student Don Bryant (left).…”