"PAM68 is found in both the plant and the cyanobacterium", Leister points out, "but it has quite different functions in the two organisms." In both cases, the newly discovered assembly factor is essential for the first steps in the construction of Photosystem II. In thale cress mutants that lack PAM68, however, these early intermediates accumulate. Inactivation of the cyanobacterial protein, on the other hand, actually facilitates the assembly of larger complexes. Strikingly, although it is required in the building of Photosystem II, PAM68 is not a member of the fully assembled, functional complex. "This is one case where the whole is less than the sum of the parts", says Leister.
The new work has uncovered common features of plant and bacterial photosynthesis, but also points to distinct differences between the two. "In the long term, a comprehensive understanding of the function of Photosystems I and II should enable us to utilize solar energy more efficiently", says Leister. It could, for instance, contribute to the development of artificial systems that mimic photosynthesis, perhaps leading to new types of solar cell. The new results will also be of interest to agronomists, as they suggest that it should be possible to produce more robust strains of crop plants that can cope with higher levels of light stress and produce better yields. At all events, Leister and his team will continue their quest for the new factors involved in photosystem assembly. (CA/suwe)
|Contact: Professor Dario Leister|