Acta Crystallographica Section D

Biological Crystallography

Volume 58, Part 7 (July 2002)

research papers

Acta Cryst. (2002). D58, 1104-1110 [ doi:10.1107/S0907444902006534 ]

Structure of cytochrome c₆ from Arthrospira maxima: an assembly of 24 subunits in a nearly symmetric shell

C. A. Kerfeld, M. R. Sawaya, D. W. Krogmann and T. O. Yeates

Abstract: Cytochrome c₆ from the cyanobacterium Arthrospira maxima is present in isoforms that can be resolved by size-exclusion chromatography. One isoform crystallized in space group I4₁32 with eight protein molecules in the asymmetric unit and a total of 384 molecules in the unit cell. Within the crystal, the molecules are arranged as clusters of 24 cytochrome c₆ molecules. Each cluster is a hollow shell with approximate octahedral (432) symmetry. Structural and biochemical studies of cytochrome c₆ isolated from other cyanobacteria and algae have led to the suggestion that cytochrome c₆ forms oligomers. The cytochrome c₆ complex described here is the largest assembly of cytochrome c₆ molecules observed thus far.

PDB reference: 1kib

Keywords: cages; protein self-assembly; electron transfer; cytochrome c₆.