Structural model and excitonic properties of the dimeric RC-LH1-PufX complex from Rhodobacter sphaeroides

Melih Şener, Jen Hsin, Leonardo G. Trabuco, Elizabeth Villa, Pu Qian, C. Neil Hunter, Klaus Schulten

Research output: Contribution to journalArticlepeer-review

Abstract

The light-harvesting apparatus of the purple bacterial photosynthetic unit consists of a pool of peripheral light-harvesting complexes that transfer excitation energy to a reaction center (RC) via the surrounding pigment-protein complex LH1. Recent electron microscopy and atomic force microscopy studies have revealed that RC-LH1 units of Rhodobacter (Rba.) sphaeroides form membrane-bending dimeric complexes together with the polypeptide PufX. We present a structural model for these RC-LH1-PufX dimeric complexes constructed using the molecular dynamics flexible fitting method based on an EM density map. The arrangement of the LH1 BChls displays a distortion near the proposed location of the PufX polypeptide. The resulting atomic model for BChl arrays is used to compute the excitonic properties of the dimeric RC-LH1 complex. A comparison is presented between the structural and excitonic features of the S-shaped dimeric BChl array of Rba. sphaeroides and the circular BChl arrangement found in other purple bacteria.

Original languageEnglish (US)
Pages (from-to)188-197
Number of pages10
JournalChemical Physics
Volume357
Issue number1-3
DOIs
StatePublished - Feb 23 2009

Keywords

  • Excitons
  • Membrane curvature
  • Molecular dynamics/flexible fitting
  • Photosynthesis
  • Purple bacteria
  • Reaction center

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Physics and Astronomy(all)

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