Structure of cytochrome c6 from Arthrospira maxima: an assembly of 24 subunits in a nearly symmetric shell
Cheryl A. Kerfeld, e-mail: [email protected]
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.
