Figure 2.

Hypothetical scheme for the evolution of Rubisco and its activases. Following the great oxidation event at least three different classes of Rubisco activase were recruited from the general molecular chaperone machinery toward a specialized Rubisco activase function in diverse autotrophic organisms. Green type and red-type Rca was maintained in eukaryotic phototrophs of the green and the red plastid lineage respectively. A phylogenetic tree was drawn using Rubisco large subunit sequences that are associated with activases. It is important to note that regarding non-red prokaryotic Rubisco sequences, many instances exist that do not have identifiable activase genes encoded in the same genome. Surface representations of a hexameric Form II Rubisco (pdb:4lf1) and spinach Form I Rubisco (pdb:8ruc) are shown. Structures shown in this paper were drawn using pymol.