The phosphorylation of light-harvesting polypeptides LHIalpha (B870) and LHIIalpha (B800-850) of Rhodobacter capsulatus B10 was higher under chemotrophic oxic than under phototrophic anoxic growth conditions.
In Rhodobacter capsulatus B10 (wild type) both alpha subunits of the light-harvesting complexes are phosphorylated during photosynthetic membrane synthesis. During the process of insertion of these polypeptides, there is a dephosphorylation resulting in intracytoplasmic membranes in which no radioactive phosphate could be detected. Moreover, we show that their phosphate-specific contents depends on the growth conditions, the highest being observed under oxic conditions. When photosynthetic membrane synthesis was induced under light and anaerobiosis, a decrease in the phosphate-specific contents ensued. An inverse relationship exists between specific phosphorylation levels and the degree of membrane differentiation. The phosphorylation is thus a transient phenomenon characteristic of the photosynthetic membrane synthesis governed by the external redox conditions constituting an additional post-transcriptional level of regulation.
Kerber
N
N
Universidad de Buenos Aires, Facultad de Agronomía y Centro de Investigaciones Bioquímicas y Fisiológicas (CIBYF-CONICET), Av. San Martín 4453, 1417 Buenos Aires, Argentina.
Pucheu
N
N
Tadros
M
M
Drews
G
G
García
A
A
D001345:Autoradiography; D002845:Chromatography; D004591:Electrophoresis, Polyacrylamide Gel; D000860:Hypoxia; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism; D010084:Oxidation-Reduction; D010766:Phosphorylation; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D016354:Rhodobacter capsulatus / Q000254:growth & development / Q000378:metabolism*; D014871:Water Microbiology
D008565:Membrane Proteins; D045322:Photosynthetic Reaction Center Complex Proteins