A fundamental understanding of cellular processes is basic to biomedical research. A central problem in cell biology is the molecular basis of the formation of differentiated biological membranes. Photosynthetic bacteria, Rhodospirillum rubrum in particular, provide an experimentally accessible model system for studies of membrane biogenesis because the membranes can easily be isolated from these bacterial cells and because the formation of the photosynthetic membrane may be manipulated genetically and by experimental conditions. Additionally these organisms offer advantages as an experimental system because 1) the primary structures of the principal membrane protein components (light-harvesting antenna and photochemical reaction center) of the photosynthetic membrane encoded by the puf and puh operons are known in four related species; 2) the X-ray structure of the photochemical reaction center is known in tow of these; 3) functional assembly of components can be assessed on the basis of spectral properties and the capacity for phototrophic growth; 4) membrane biogenesis studies clearly indicate that these organisms do have a mechanism to target proteins to specific sites in a membrane continuum. Our previous studies have demonstrated the necessity of the puf and puh gene products for photosynthetic membrane formation implying that insertion of these proteins into the membrane causes membrane proliferation. In addition in preliminary studies several seminal observations have been made that will open new paths of investigation. The long-term goal of this project is to understand the molecular events involved in membrane formation. In the proposed research, the minimal requirements for membrane protein assembly and membrane proliferation will be evaluated. Mutants that lack one or more photochemical components will be characterized to shed light on the role of these components in membrane assembly. This characterization will include biochemical and ultrastructural analysis. The effect of mutations at specific sites in these components will then be evaluated to determine the role of protein structure in membrane assembly, including the role of protein-protein and protein-membrane interactions in development. The understanding achieved through experimentation with this simple and well-defined model system will have implications in cellular processes involved in health and disease.
| Brantner, C A; Buchholz, L A; Remsen, C C et al. (2000) Isolation of intracytoplasmic membrane from the methanotrophic bacterium Methylomicrobium album BG8. Curr Microbiol 40:132-4 |
| Cheng, Y S; Brantner, C A; Tsapin, A et al. (2000) Role of the H protein in assembly of the photochemical reaction center and intracytoplasmic membrane in Rhodospirillum rubrum. J Bacteriol 182:1200-7 |
