Occurrence of Secondary Carotenoids in PS I Complexes Isolated from Eremosphaera viridis De Bary (Chlorophyceae)

Abstract

Abstract Photosystem I complexes of Eremosphaera viridis De Bary (Chlorophyceae, Chlorococcales) were isolated and partially characterized. In the isolated PS I complexes, peptides of 64-60, 26, 23, 20, 15, 11 and 8.5 kDa could be detected. When Eremosphaera was grown under regular conditions the pigment composition of the isolated PS I complexes was similar to that found in PS I complexes from other green algae. However, when Eremosphaera was grown under nitrogen deficient conditions, PS I complexes contained the secondary carotenoids canthaxanthin and traces of astaxanthin and echinenone in addition to β-carotene, violaxanthin and lutein. The results presented indicate that the secondary carotenoids are associated with the LHC I of PS I. To our knowledge this represents the first report about the association of secondary carotenoids with light harvesting pigment protein complexes of green algae.