Photosynthetic reaction center-light harvesting 1 (RC-LH1) core supercomplexes are essential for energy capture and electron transport in purple bacteria. Rhodospirillum rubrum, a model organism for bacterial photosynthesis, features an RC-LH1 architecture with a closed LH1 ring and lacks the peripheral LH2 antenna in the photosynthetic membranes. How this unique RC-LH1 supercomplex performs energy transfer and quinone transport remains unclear. Here, we characterized both the structural and functional properties of Rsp. rubrum RC-LH1 supercomplex using cryo-electron microscopy (cryo-EM), transient absorption (TA) spectroscopy, and cytochrome c