Protein components of bacterial photosynthetic membranes

Topology and growth of the intracytoplasmic membrane system of Rhodopseudomonas spheroides: protein, chlorophyll, and phospholipid insertion into steady-state anaerobic cells

An equilibrium density gradient centrifugation study involving the separation of "old" and "new" membranes has been developed to determine the manner in which protein, lipid, and chlorophyll are incorporated into growing intracytoplasmic membranes (chromatophores) of Rhodopseudomonas spheroides. Chromatophores derived from cells grown in an H(2)O-medium had a density of 1.175 to 1.180 g/cm(3) and were readily separable from chromatophores having a density of 1.220 to 1.230 isolated from cells grown in a 70% D(2)O-medium. After a shift from "D(2)O-" to "H(2)O"-based media, only hybrid chromatophores derived from a combination of "heavy" (old) and "light" (new) chromatophore material could be detected. The experimentally determined, median density values for the growing intracytoplasmic membrane system followed a theoretically determined profile which was calculated from the density of full "heavy" and full "light" material assuming random, homogeneous incorporation of new material into old membrane. The distribution of the radioactive labels for protein (leucine) and chlorophyll (delta-aminolevulinic acid) were identical and showed a reproducible displacement of the "old" material to the heavy side of the optical density at 365 nm (OD(365)) absorbance and a displacement of the "new" material to the light side of the OD(365) absorbance profile. Specific phospholipid growth showed no displacement for either the "old" or "new" material from the median absorbance profile.

Proteins specified by herpes simplex virus. Staining and radiolabeling properties of B capsid and virion proteins in polyacrylamide gels

ANALYSES OF THE STRUCTURAL PROTEINS OF HERPES SIMPLEX VIRIONS AND OF CAPSIDS CONTAINING VIRAL DNA (B CAPSIDS), AFTER ELECTROPHORESIS IN POLYACRYLAMIDE GELS, REVEALED CONSIDERABLE VARIABILITY IN THEIR PROPERTIES WITH RESPECT TO: (i) retention of Coomassie brilliant blue (CBB) and fast green stains during destaining, (ii) relative optical absorbance of the CBB-protein complex at different wavelengths, (iii) relative efficiency with which (14)C-amino acids are incorporated during early and late periods of the infection cycle, and (iv) capacity to be phosphorylated in vivo. In addition, it was found that protein 22a of B capsids, which does not have an electrophoretically identical counterpart in virions, shares a relatively unique set of staining and radiolabeling properties with virion protein 22, which has a slightly more rapid electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gels.

Coupling between bacteriochlorophyll and membrane protein synthesis in Rhodopseudomonas spheroides

Bacteriochlorophyll-containing membranes from Rhodopseudomonas spheroides contain proteins with estimated molecular weights of 26,000, 22,000, 19,000, and 10,000-6,000 (proteins 9, 10, 11, and 15) when analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Proteins 9, 10, and 11 may be associated with the reaction center form of bacteriochlorophyll and protein 15, with the light-harvesting form. These proteins were not detected in membranes from nonpigmented wild-type cells grown with high aeration. Proteins 10, 11, and 15 were not found in mutants with blocks in bacteriochlorophyll synthesis, including strain 8-17, which is blocked at the phytolation step. Protein 9 was found in significantly reduced amounts. Apparently, synthesis of the completed bacteriochlorophyll molecule is required for the occurrence of these proteins in the membrane. Gel autoradiography was used to follow the synthesis of membrane proteins in mutant H-5, which requires delta-aminolevulinic acid for bacteriochlorophyll synthesis. Incorporation of labeled amino acids into proteins 9 and 15 was curtailed preferentially in cells deprived of delta-aminolevulinic acid.