Significance of protein crowding, order and mobility for photosynthetic membrane functions

Biochem Soc Trans. 2008 Oct;36(Pt 5):967-70. doi: 10.1042/BST0360967.

Abstract

Natural photosynthesis requires diffusion-based processes either for the functional communication of protein complexes or for the adaptation, maintenance and biogenesis of the photosynthetic apparatus. A conceptual problem with lateral diffusion in photosynthetic membranes arises from the fact that these membranes are densely packed with membrane integral protein complexes (molecular crowding). Theoretical analysis of PQ (plastoquinone) and protein diffusion in higher plant grana thylakoids reveal very inefficient lateral diffusion. In contrast, measurement of protein mobility in grana membranes shows that a fraction of protein complexes can move surprisingly fast. It is postulated that organization of protein complexes in supercomplexes and large-scale ordering of Photosystem II and light-harvesting complex II could be strategies for the optimization of diffusion in crowded thylakoid membranes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Diffusion
  • Electron Transport / physiology
  • Intracellular Membranes / metabolism*
  • Intracellular Membranes / ultrastructure
  • Models, Molecular
  • Photosynthesis / physiology*
  • Photosynthetic Reaction Center Complex Proteins / chemistry
  • Photosynthetic Reaction Center Complex Proteins / metabolism*
  • Plant Proteins / chemistry
  • Plant Proteins / metabolism*
  • Plastoquinone / metabolism*
  • Protein Conformation
  • Thylakoids / metabolism
  • Thylakoids / ultrastructure*

Substances

  • Photosynthetic Reaction Center Complex Proteins
  • Plant Proteins
  • Plastoquinone