Crystal Structure of the RC-LH1 Core Complex from Rhodopseudomonas palustris

Abstract

The crystal structure at 4.8 angstrom resolution of the reaction center–light harvesting 1 (RC–LH1) core complex from Rhodopseudomonas palustris shows the reaction center surrounded by an oval LH1 complex that consists of 15 pairs of transmembrane helical α- and β-apoproteins and their coordinated bacteriochlorophylls. Complete closure of the RC by the LH1 is prevented by a single transmembrane helix, out of register with the array of inner LH1 α-apoproteins. This break, located next to the binding site in the reaction center for the secondary electron acceptor ubiquinone (UQ B ), may provide a portal through which UQ B can transfer electrons to cytochrome b/c 1 .