title: Native Mass Spectrometry Characterizes the Photosynthetic Reaction Center Complex from the Purple Bacterium Rhodobacter sphaeroides.
abstract: Native mass spectrometry (MS) is an emerging approach to study protein complexes in their near-native states and to elucidate their stoichiometry and topology. Here, we report a native MS study of the membrane-embedded reaction center (RC) protein complex from the purple photosynthetic bacterium Rhodobacter sphaeroides. The membrane-embedded RC protein complex is stabilized by detergent micelles in aqueous solution, directly introduced into a mass spectrometer by nano-electrospray (nESI), and freed of detergents and dissociated in the gas phase by collisional activation. As the collision energy is increased, the chlorophyll pigments are gradually released from the RC complex, suggesting that native MS introduces a near-native structure that continues to bind pigments. Two bacteriochlorophyll a pigments remain tightly bound to the RC protein at the highest collision energy. The order of pigment release and their resistance to release by gas-phase activation indicates the strength of pigment interaction in the RC complex. This investigation sets the stage for future native MS studies of membrane-embedded photosynthetic pigment-protein and related complexes.Graphical Abstract.
authors: Department of Chemistry, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA.|Photosynthetic Antenna Research Center, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA.
authors: Hao
authors: H
authors: Zhang
authors: Department of Chemistry, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA.
authors: Lucas B
authors: LB
authors: Harrington
authors: Department of Chemistry, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA.|Photosynthetic Antenna Research Center, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA.
authors: Yue
authors: Y
authors: Lu
authors: Department of Biology, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA.|Photosynthetic Antenna Research Center, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA.
authors: Mindy
authors: M
authors: Prado
authors: Department of Biology, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA.|Photosynthetic Antenna Research Center, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA.
authors: Rafael
authors: R
authors: Saer
authors: Department of Chemistry, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA.
authors: Don
authors: D
authors: Rempel
authors: Department of Chemistry, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA. blankenship@wustl.edu.|Department of Biology, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA. blankenship@wustl.edu.|Photosynthetic Antenna Research Center, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA. blankenship@wustl.edu.
authors: Robert E
authors: RE
authors: Blankenship
authors: Department of Chemistry, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA. mgross@wustl.edu.|Photosynthetic Antenna Research Center, Washington University in St. Louis, One Brookings Dr., St. Louis, MO, 63130, USA. mgross@wustl.edu.
authors: Michael L
authors: ML
authors: Gross
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry*; D002734:Chlorophyll / Q000737:chemistry; D003902:Detergents / Q000737:chemistry; D008823:Micelles; D008958:Models, Molecular; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry*; D012242:Rhodobacter sphaeroides / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods
chemical_list: D001426:Bacterial Proteins; D003902:Detergents; D008823:Micelles; D045322:Photosynthetic Reaction Center Complex Proteins; D002734:Chlorophyll
keywords: Membrane protein complex; Native mass spectrometry; Photosynthesis; Pigment–protein interactions; Purple bacterium; Reaction center