The thylakoid membranes of cyanobacteria: structure, dynamics and function

In recent years there has been remarkable progress in determining the three-dimensional structures of photosynthetic complexes. A new challenge is emerging: can we understand the organisation and interaction of those complexes in the intact photosynthetic membrane? Intact membranes are complex, dynamic systems. If we are to understand the function of the intact membrane, we will need to understand the organisation of the complexes, how they can diffuse and interact in the membrane, how they are assembled, repaired and broken down, and how their function is regulated. Cyanobacteria have some crucial advantages as model systems. The complete sequencing of the Synechocystis 6803 genome, coupled with the ease of genetic manipulation of Synechocystis (and certain other cyanobacteria) have given us a unique tool for studying a photosynthetic organism. Furthermore, some cyanobacteria have a very simple, regular thylakoid membrane structure. The unique geometry of photosynthetic membranes of these cyanobacteria will greatly facilitate biophysical studies of membrane function. This review summarises recent progress in understanding the structure, function and dynamics of cyanobacterial thylakoid membranes, highlights the questions that remain to be answered and suggests some possible approaches towards solving those questions.