Translocation of precytochrome c2 into intracytoplasmic membrane vesicles of Rhodobacter capsulatus requires a peripheral membrane protein.
Rhodobacter capsulatus is a member of the group of alpha-purple bacteria which are closely related to the ancestral endosymbiont that gave rise to mitochondria. It has therefore been hypothesized that the molecular mechanisms governing protein export in alpha-purple bacteria have been conserved during the evolution of mitochondria. To enable analysis of protein export in alpha-purple bacteria we describe here the development of a homologous cell-free synthesis/export system consisting entirely of components of R. capsulatus. Translocation of precytochrome c2 into intracytoplasmic membrane vesicles of this organism was found to require the proton-motive force and proceed at a significantly higher efficiency when membranes were present during protein synthesis. Furthermore, we show that, in this cell-free system, translocation depends on a preparation of peripheral membrane proteins which do not possess detectable SecA- and SecB-like activities.
Institute of Biochemistry, University of Freiburg, Germany.
B
B
Wieseler
M
M
Müller
D001426:Bacterial Proteins / Q000378:metabolism*; D001693:Biological Transport, Active; D002474:Cell-Free System; D003574:Cytochrome c Group / Q000378:metabolism*; D004563:Electrochemistry; D007425:Intracellular Membranes / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D009994:Osmolar Concentration; D011498:Protein Precursors / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011522:Protons; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016354:Rhodobacter capsulatus / Q000378:metabolism*
D001426:Bacterial Proteins; D003574:Cytochrome c Group; D008565:Membrane Proteins; D011498:Protein Precursors; D011522:Protons; D011993:Recombinant Fusion Proteins; D006180:Proton-Translocating ATPases