Differential Association of the Light-Harvesting Proteins (FCPs) with PSⅠ and PSⅡ in the Small Brown Tide Alga Aureococcus Anophagefferens

摘要

Aureococcus anophagefferens is a picoplanktonic microalga that is very well adapted to growth at low nutrient and low light levels, causing devastating blooms ("brown tides")-Its thylakoid membranes have a high content of FCPs (fucoxanthin/Chl a/c-binding proteins) belonging to the light harvesting complex (LHC) superfamily. Its genome sequence shows the presence of at least 64 genes for FCPs. To begin to understand the protein organization of the thylakoid, the membranes were solubilized with dodecyl maltoside and analyzed by sucrose gradients. Some of the FCPs appear to be organized in supercomplexes of 140 and 240 kDa where they are associated with PSⅡ, while others might form independent supercomplexes. This protein organization probably reflects the ability of this alga to grow to very high cell densities in nature, with consequent limitation of incident light intensity due to shading.