Open AccessThe localization of pigment‐binding polypeptides in membranes of Rhodopseudomonas viridis
Author(s) -
Tadros Monier Habib,
Spormann Dirk,
Drews Gerhart
Publication year - 1988
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1988.tb02808.x
Subject(s) - vesicle , proteinase k , amino acid , biochemistry , membrane , purple bacteria , photosynthetic reaction centre , biology , rhodospirillaceae , protein subunit , rhodopseudomonas , pigment , cytoplasm , photosynthesis , rhodospirillales , biophysics , chemistry , enzyme , organic chemistry , gene
Inside‐out and right‐side out vesicles were isolated from the intracytoplasmic membrane system of the photosynthetic bacterium Rhodopseudomonas viridis and treated with proteinase K. Afterwards the pigment‐binding proteins of the photosynthetic apparatus were extracted from the membrane, purified and the N‐ and C‐terminal amino acyl sequences determined. Forty‐eight amino acids were found to be removed from the N‐terminal domain of the M‐subunit and twenty‐eight amino acids split off the L‐subunit of reaction center when inside‐out vesicles were digested with proteinase K. Six amino acids of the N‐terminal region of the beta polypeptide of the light‐harvesting complex B1020 were removed when inside‐out vesicles were treated with proteinase K. The N‐terminal domains of alpha and gamma polypeptides of the antenna complex B1020 were not cleaved by proteinase K either in right‐side out or in inside‐out vesicles. It is concluded that the N‐terminal domains of M‐, L‐ and β‐subunits are exposed and accessible to proteinase K on the cytoplasmic surface of the membrane. This is in agreement with results obtained with other photosynthetic bacteria. The orientation of the other light‐harvesting polypeptides is discussed.