Updated project metadata. Rhodopseudomonas palustris is a species of purple phototrophic bacterium. In these species, solar energy is captured by reaction centre-light harvesting 1 (RC-LH1) complexes which reside in membranes within the cells. The RC comprises three protein subunits: H, M, L and is encircled by a ring of LH1-α and LH1-β subunit pairs. Approximately 10% of these complexes in the wild-type (WT) strain include an additional subunit called protein-W. In this project, we have determined cryo-EM structures for RC-LH1 complexes both with and without protein-W. To enable the purification of RC-LH1-W with 100% occupancy of protein-W, strain expressing a C-terminally His-tagged W was engineered. For complexes lacking W, a knockout strain was used. Proteomic analysis was employed to validate these strains and establish that the WT and W-His expressed similar levels of W relative to RC-LH1.