27 November 2003

Structural biology: The go-between

The atomic structure of cytochrome b₆f, the last major complex of oxygenic photosynthesis for which the atomic structure was unknown, has now been solved. Cytochrome b₆f transfers electrons between photosystems I and II to balance their activities during different light conditions. It also uses the energy of these electrons to pump protons across the chloroplast membrane. The structure reveals the location of two cofactors whose function has remained mysterious, chlorophyll a and β-carotene. It also uncovers the existence of an unsuspected fourth haem whose central iron atom is coordinated in an unusual way. This and the haem's position in the cytochrome make it a key intermediate in electron transduction.

An atypical haem in the cytochrome b₆f complex
DAVID STROEBEL, YVES CHOQUET, JEAN-LUC POPOT & DANIEL PICOT
Nature 426, 413–418 (2003); doi:10.1038/nature02155
| Summary | Full Text (HTML / PDF) |

Structural biology: Dual approach to a light problem
WERNER K�HLBRANDT
The structure of the last of the major pigment-containing protein complexes involved in photosynthesis is now revealed. The details complete our picture of electron shuttling in this vital process.
Nature 426, 399–400 (2003); doi:10.1038/426399a
| Full Text (HTML / PDF) |

27 November 2003 table of contents