title: Cyanobacterial photosynthesis in the oceans: the origins and significance of divergent light-harvesting strategies.
abstract: Prochlorococcus and Synechococcus are abundant unicellular cyanobacteria and major participants in global carbon cycles. Although they are closely related and often coexist in the same ocean habitat, they possess very different photosynthetic light-harvesting antennas. Whereas Synechococcus and the majority of cyanobacteria use phycobilisomes, Prochlorococcus has evolved to use a chlorophyll a(2)/b(2) light-harvesting complex. Here, we present a scenario to explain how the Prochlorococcus antenna might have evolved in an ancestral cyanobacterium in iron-limited oceans, resulting in the diversification of the Prochlorococcus and marine Synechococcus lineages from a common phycobilisome-containing ancestor. Differences in the absorption properties and cellular costs between chlorophyll a(2)/b(2) and phycobilisome antennas in extant Prochlorococcus and Synechococcus appear to play a role in differentiating their ecological niches in the ocean environment.
authors.affiliation: Dept of Biology, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139, USA.
authors.forename: Claire S
authors.initials: CS
authors.lastname: Ting
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Rocap
authors.forename: Jonathan
authors.initials: J
authors.lastname: King
authors.forename: Sallie W
authors.initials: SW
authors.lastname: Chisholm
mesh_terms: D005075:Biological Evolution; D000458:Cyanobacteria / Q000235:genetics / Q000502:physiology*; D017753:Ecosystem; D008027:Light; D045342:Light-Harvesting Protein Complexes; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics; D045524:Phycobilisomes; D011506:Proteins / Q000235:genetics; D012623:Seawater / Q000382:microbiology*
chemical_list: D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; D045524:Phycobilisomes; D011506:Proteins