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Localization of the N‐terminal regions of the B870α,β and of reaction center L polypeptides on the cytoplasmic surface of the chromatophores of Rhodopseudomonas capsulata
Author(s) -
Tadros Monier Habib,
Frank Rainer,
Drews Gerhart
Publication year - 1986
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(86)80253-8
Subject(s) - chromatophore , photosynthetic reaction centre , periplasmic space , cytoplasm , vesicle , membrane , chemistry , transmembrane protein , transmembrane domain , biophysics , biochemistry , mutant , stereochemistry , biology , photosynthesis , escherichia coli , receptor , fishery , gene
Chromatophores (intracytoplasmic inside‐out membrane vesicles) from the mutant strain Ala+ of Rhodopseudomonas capsulata were treated with proteinase K in order to determine the orientation of the pigment‐binding polypeptides of the photochemical reaction center and of the light‐harvesting complex B870. Nine amino acid residues of the B870α polypeptide were cleaved up to position Leu 9 ‐Val 10 of the N‐terminus and 22 residues up to position Val 22 ‐Tyr 23 of the β‐chain N‐terminus. From the reaction center L‐chain the N‐terminus up to position 27 (Val) was split off. The C‐termini of the B870α and β polypeptides including the hydrophobic α‐helical transmembrane portion remained intact. It is concluded that the N‐terminal region of the pigment‐binding polypeptides α and β of the B870 light‐harvesting complex and of the L‐chain of the reaction center point to the cytoplasm while the C‐termini of the B870α,β polypeptides are exposed or pointing toward the periplasmic membrane surface.