Abstract
The green sulfur bacteria are strictly anaerobic photo-autotrophic organisms. Their reaction center (RC) complexes are classified into the PS I-type RC. Their RC core protein is a homodimer, while the other well-known ones are heterodimers whose tertiary structures have already been determined. The detailed mechanisms on electron transfer reactions within green sulfur bacterial RC remain to be resolved because it is too unstable to be analyzed by various biochemical and spectroscopic methods under aerobic conditions. Molecular identification of all electron transfer cofactors has not yet been done. Especially, it has still been controversial whether quinone molecule exists and functions as a secondary acceptor. Molecular biological methods, such as the addition of some affinity tag and/or the site directed mutagenesis, are therefore expected to cope with these issues. In this study, we constructed a gene expression system to introduce the tagged core protein in the green sulfur bacterium Chlorobium tepidum.
