Summary 167

I. INTRODUCTION 168

II. THE IMPACT OF PROTEIN STRUCTURAL INFORMATION ON THE UNDERSTANDING OF THE PRIMARY REACTIONS IN PHOTOSYNTHESIS 169

1. The structure of the purple bacterial reaction centre 170

2. The structure of PSI 172

3. The structure of PSII 173

4. The structure of antenna complexes 176

(a) Light-harvesting complexes from purple photosynthetic bacteria 177

III. DEVELOPING OVEREXPRESSION SYSTEMS FOR THE STUDY OF PLANT PROTEIN 188

1. Expression of heterologous proteins in Escherichia coli 189

2. Protein expression in the methylotrophic yeast Pichia pastoris 189

3. Expression of recombinant protein in insect cells: the baculovirus system 190

IV. CONCLUSIONS 190

This review sets out the case that now is the time for plant science to establish the technologies required for routinely studying the structure and function of plant proteins. The impact that protein structural information can have is illustrated here with reference to photosynthesis. Our understanding of the precise molecular mechanisms of the light-reactions of photosynthesis has been transformed by the combination of high-resolution protein structural data and detailed functional studies. The past few years have been a particularly exciting time to be engaged in basic plant science research. The application of modern techniques of molecular biology has allowed many key questions to be addressed. The stage is now set for an even bigger revolution as the current plant genome sequencing projects are completed. If these advances are going to be fully exploited, plant science must get to grips with studying proteins, not just genes. Reliable methods for the overexpression of proteins in their native state coupled with routine access to structure determination must become the norm rather than the exception. In 1998 there were about 9000 protein structures deposited in the Brookhaven database. Very few of these are plant proteins. This trend will have to be reversed if research in molecular plant science is to fulfil its potential.