Assembly and structural organization of pigment-protein complexes in membranes of Rhodopseudomonas sphaeroides

Journal Article · Fri Jan 01 04:00:00 EST 1982 · Prog. Clin. Biol. Res.; (United States)

OSTI ID:5624185

Hunter, C N; Pennoyer, J D; Niederman, R A

The B875 and B800-850 light-harvesting pigment-protein complexes of Rhodopseudomonas sphaeroides are characterized further by lithium dodecyl sulfate/polyacrylamide gel electrophoresis at 4 degrees C. Bacteriochlorophyll a was shown in reconstruction studies to remain complexed with its respective binding proteins during this procedure. From distributions in these gels, a quantitative description for the arrangement of the complexes is proposed. Assembly of the complexes was examined in delta-aminolevulinate-requiring mutant H-5 after a shift from high- to low-light intensity. After 10 h of delta-(/sup 3/H)aminolevulinate labeling, the specific radioactivity of bacteriochlorophyll in a fraction containing putative membrane invaginations reached the maximal level, while that of the mature photosynthetic membrane was at only one-third this level. This suggests that membrane invaginations are sites of preferential bacteriochlorophyll synthesis in which completed pigment-proteins exist transiently. Analysis of the /sup 3/H distribution after electrophoretic separation further suggests that photosynthetic membranes grow mainly by addition of B800-850 to preformed membrane consisting largely of B875 and photochemical reaction centers. These results corroborate the above model for the structural organization of the light-harvesting system and indicate that the structurally and functionally discrete B800-850 pool is not completely assembled until all B875 sites for B800-850 interactions are occupied.

• Research Organization: Department of Biochemistry, Rutgers University, Piscataway, NJ
• OSTI ID: 5624185
• Journal Information: Prog. Clin. Biol. Res.; (United States), Journal Name: Prog. Clin. Biol. Res.; (United States) Vol. 102; ISSN PCBRD
• Country of Publication: United States
• Language: English

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BACTERIA
CARBOXYLIC ACIDS
CHEMICAL BONDS
CHLOROPHYLL
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PHYTOCHROMES
PIGMENTS
PORPHYRINS
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RHODOPSEUDOMONAS
TRACER TECHNIQUES
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