Open AccessLocalization of the exposed N-terminal region of the B800-850 alpha and beta light-harvesting polypeptides on the cytoplasmic surface of Rhodopseudomonas capsulata chromatophores
Author(s) -
Monier H. Tadros,
Rainer Frank,
Gerhart Drews
Publication year - 1986
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.167.1.96-100.1986
Subject(s) - biology , biochemistry , transmembrane protein , cytoplasm , periplasmic space , transmembrane domain , proteinase k , rhodospirillales , amino acid , biophysics , enzyme , escherichia coli , receptor , gene
Proteinase K and trypsin were used to determine the orientation of the light-harvesting B800-850 alpha and beta polypeptides within the chromatophores (inside-out membrane vesicles) of the mutant strain Y5 of Rhodopseudomonas capsulata. With proteinase K 7 amino acid residues of the B800-850 alpha polypeptide were cleaved off up to position Trp-7--Thr-8 of the N terminus, and 11 residues were cleaved off up to position Leu-11-Ser-12 of the beta chain N terminus. The C termini of the B800-850 alpha and beta polypeptides, including the hydrophobic transmembrane portions, remained intact. It is proposed that the N termini of the alpha and beta subunits, each containing one transmembrane alpha-helical span, are exposed on the cytoplasmic membrane surface and the C termini are exposed to or directed toward the periplasm.