A PHOSPHORYLATED NON-ANTENNA COMPLEX PROTEIN IS PRESENT IN RHODOVULUM SULFIDOPHILUM PURIFIED MEMBRANES

LAURA J. RAIGER-IUSTMAN; NORMA L. PUCHEU; NORMA L. KERBER; AUGUSTO F. GARCIA

Bariloche, Río Negro

Congreso; XXIX Reunión anual de la Sociedad Argentina en investigación en Bioquímica y Biología Molecular; 2003

SAIB

In Rhodovulum sulfidophilum intracytoplasmic membranes appears a low molecular weight protein (6 kDa aprox, concordant to the antenna complex proteins), that is phosphorylated in-vivo under different condition.   We analyzed the phosphorylation in three strains: the wild type strain Rhodovulum sulfidophilum W4, an LHII- mutant EK281 and the LHI- mutant rsLRI constructed in our laboratory. All of them showed the phosphorylated protein, determining that this protein did not correspond to any antenna complex protein described until now. To determine if this protein is associated to one photosynthetic complex in particular, we treated the purified membranes with a non ionic detergent (LDAO) and separated the different complexes with a sucrose gradient. Three fractions were obtained: the heaviest corresponding to a fraction enriched in CR-LHI complex (fraction 1) the second corresponding to the LHII complex (fraction 2) and the lightest (fraction 3) corresponding to a heterogenic fraction that could contain the intracytoplasmic growing initiation sites. The phosphorylated protein appears only in this lightest fraction.