SINGLE CORE POLYPEPTIDE IN THE REACTION-CENTER OF THE PHOTOSYNTHETIC BACTERIUM HELIOBACILLUS-MOBILIS - STRUCTURAL IMPLICATIONS AND RELATIONS TO OTHER PHOTOSYSTEMS
U. Liebl et al., SINGLE CORE POLYPEPTIDE IN THE REACTION-CENTER OF THE PHOTOSYNTHETIC BACTERIUM HELIOBACILLUS-MOBILIS - STRUCTURAL IMPLICATIONS AND RELATIONS TO OTHER PHOTOSYSTEMS, Proceedings of the National Academy of Sciences of the United Statesof America, 90(15), 1993, pp. 7124-7128
The gene for a reaction center core polypeptide from the anoxygenic ph
otosynthetic bacterium Heliobacillus mobilis was cloned and sequenced.
The deduced amino acid sequence consists of 609 residues with a molec
ular mass of 68 kDa. An adjacent open reading frame is not transcribed
under our experimental conditions. No evidence for a second related r
eaction center core gene was found. The primary sequence of the reacti
on center protein (P800 protein) shows a high percentage of sequence i
dentity to photosystem I in a cysteine-containing loop, which is the p
utative binding site of the iron-sulfur center F(X) and in the precedi
ng hydrophobic region. Our data imply a homodimeric organization of th
e reaction center. This is fundamentally different from photosystem I
and most other photosynthetic reaction centers, where the reaction cen
ter core is composed of two similar but nonidentical subunits.