Photosynthetic reaction centers: interfacing molecular genetics and optical spectroscopy

In the elucidation of the mechanism by which certain photosynthetic bacteria convert light into chemical energy, genetics has become intertwined with biophysical techniques. While X-ray crystallography has yielded an atomic resolution structure of the photosynthetic reaction center (RC), optical spectroscopy remains the most important technique for screening mutants. Newly developed imaging devices and genetic techniques should enable biophysicists to characterize rapidly the spectra of extremely large numbers of RC and light harvesting (LH) antennae mutants. The intrinsic pigments of the RC and LH antennae act as spectroscopic reporters for assembly and function of these integral membrane proteins. To optimize this genetics/spectroscopy interface, new algorithms that relate the structure of the genetic code to the physico-chemical properties of the amino acids are being developed to design libraries of mutants.