Antenna ring around trimeric Photosystem I in chlorophyll b containing cyanobacterium Prochlorothrix hollandica.
Prochlorothrix hollandica is one of the three known species of an unusual clade of cyanobacteria (formerly called "prochlorophytes") that contain chlorophyll a and b molecules bound to intrinsic light-harvesting antenna proteins. Here, we report the structural characterization of supramolecular complex consisting of Photosystem I (PSI) associated with the chlorophyll a/b-binding Pcb proteins. Electron microscopy and single particle image analysis of negatively stained preparations revealed that the Pcb-PSI supercomplex consists of a central trimeric PSI surrounded by a ring of 18 Pcb subunits. We conclude that the formation of the Pcb ring around trimeric PSI represents a mechanism for increasing the light-harvesting efficiency in chlorophyll b-containing cyanobacteria.
Bumba
Ladislav
L
Institute of Plant Molecular Biology, Czech Academy of Sciences, Branisovska 31, 37005 Ceske Budejovice, Czech Republic. bumba@seznam.cz
Prasil
Ondrej
O
Vacha
Frantisek
F
D002499:Centrifugation, Density Gradient; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry / Q000648:ultrastructure; D008854:Microscopy, Electron; D045331:Photosystem I Protein Complex / Q000648:ultrastructure*; D019692:Prochlorothrix / Q000648:ultrastructure*; D020836:Protein Structure, Quaternary
D045342:Light-Harvesting Protein Complexes; D045331:Photosystem I Protein Complex