1. Martin, J. H. et al. Testing the iron hypothesis in ecosystems of the equatorial PaciÆc Ocean. Nature.
371, 123±129 (1994).
2. Behrenfeld, M. J., Bale, A. J., Zbigniew, S. K., Aiken, J. & Falkowski, P. G. ConÆrmation of the iron
limitation of phytoplankton photosynthesis in the equatorial PaciÆc Ocean. Nature 383, 508±511
(1996).
3. Straus, N. A. in Molecular Biology of Cyanobacteria (ed. Bryant, D. A.) 731±750 (Kluwer Academic,
Dordrecht, 1994).
4. Burnap, R. L., Troyan, T. & Sherman, L. A. The highly abundant chlorophyll-protein complex of irondeÆcient
Synechococcus sp. PCC7942 (CP439) is encoded by the isiA gene. Plant Physiol. 103, 893±902
(1993).
5. Falk, S., Samson, G., Bruce, D., Hunter, N. P. A. & Laudenbach, D. A. Functional analysis of the ironstress
induced CP439 polypeptide of PSII in the cyanobacterium Synechococcus sp. PCC 7942.
Photosynth. Res. 45, 51±60 (1995).
6. Park, Y. P. Sandstro»m, S., Gustafsson, P. & O»
quist, G. Expression of the isiA gene is essential for the
survival of the cyanobacterium Synechococcus sp. PCC 7942 by protecting photosystem II from excess
light under iron limitation. Mol. Microbiol. 32, 123±129 (1999).
7. Bricker, T. M., Morvant, J., Marsi, N., Sutton, H. M. & Frankel, L. K. Isolation of a highly active
photosystem II preparation from Synechocystis 6803 using a histidine-tagged mutant of CP47.
Biochim. Biophys. Acta. 1409, 50±57 (1998).
8. Ro»gner, M.,Mu hlenhoff, U., Boekema, E. J. &Witt, H. T. Mono-, di- and trimeric PSI reaction center
complexes isolated from the thermophilic cyanobacterium Synechococcus sp. Size, shape and activity.
Biochim. Biophys. Acta 1015, 415±424 (1989).
9. Boekema, E. J., Boonstra, A. F., Dekker, J. P. & Ro»
gner, M. Electron microscopic structural analysis of
photosystem I, photosystem II, and the cytochrome b6f complex from green plants and cyanobacteria.
J. Bioenerg. Biomembr. 26, 17±29 (1994).
10. Kraub, N. et al. Photosystem I at 4 A
resolution represents the Ærst structural model of a joint
photosynthetic reaction centre and core antenna system. Nature Struct. Biol. 3, 965±973 (1996).
11. Zouni, A. et al. Crystal structure of photosystem II from Synechococcus elongatus at 3.8A resolution.
Nature 409, 739±743 (2001).
12. Hankamer, B., Morris, E. P. & Barber, J. Revealing the structure of the oxygen evolving core dimer of
photosystem II by cryoelectron crystallography. Nature Struct. Biol. 6, 560±564 (1999).
13. Schubert, W.-D. et al. Photosystem I of Synechococcus elongatus at 4 A
resolution: Comprehensive
structural analysis. J. Mol. Biol. 272, 741±769 (1997).
14. McDermott, G. et al. Crystal structure of an integral membrane light-harvesting complex from
photosynthetic bacteria. Nature 374, 517±521 (1995).
15. Cogdell, R. J. et al. How photosynthetic bacteria harvest solar energy. J. Bacteriol. 181, 3869±3879
(1999).
16. Williams, J. G. K. Construction of speciÆc mutants in PSII photosynthetic reaction centres by genetic
engineering methods in Synechocystis 6803. Methods Enzymol. 167, 766±778 (1988).
17. Tang, X.-S. & Diner, B. A. Biochemical and spectroscopic characterisation of a new oxygen-evolving
photosystem II core complex from the cyanobacterium Synechocystis PCC 6803. Biochemistry 33,
4594±4603 (1994).
18. Hankamer, B. et al. Isolation and biochemical characterisation of monomeric and dimeric photosystem
II complexes from spinach and their relevance to the organisation of photosystem II in vivo.
Eur. J. Biochem. 243, 422±429 (1997).
19. van Heel, M., Harauz, G. & Orlova, E. V. A new generation of the IMAGIC image processing system.
J. Struct. Biol. 116, 17±24 (1996).
20. van Heel, M. et al. Single-particle electron cryo-microscopy: towards atomic resolution. Q. Rev.
Biophys. 33, 307±369 (2000).
21. Sherman, M., Soejima, T., Chui, W. & van Heel, M. Multi-variate analysis of single unit cells in
electron crystallography. Ultramicroscopy 74, 179±199 (1998).
22. Guex, N. & Peitsch, M. C. SWISS-MODEL and the Swiss-Pdb Viewer: An environment for
comparative protein modeling. Electrophoresis 18, 2714±2723 (1997).