The complete amino acid sequence of a bacteriochlorophyll a binding polypeptide isolated from the cytoplasmic membrane of the green photosynthetic bacterium Chloroflexus aurantiacus

AbstractA polypeptide soluble in organic solvents was isolated from whole membrane fractions of the green thermophilic bacterium Chloroflexus aurantiacus by chromatography on Sephadex LH-60, Whatman DE-32 and Bio Gel P-10. The complete amino acid sequence of this 4.9 kDa polypeptide (44 amino acid residues) was determined. The polypeptide shows a 3-domain structure, similar to the domain structure of the antenna BChI polypeptides of purple photosynthetic bacteria, and sequence homologies (27–39%) to the light-harvesting α-polypeptides of the B870 (890) antenna complexes from purple bacteria. Therefore, the 4.9 kDa polypeptide is designated B(808-866)-α. The typical His residue (conserved His residue identified in all antenna polypeptides of purple bacteria as possible BChI binding site) is found within the hydrophobic domain, which extends from Asn 10 to Leu 30