Abstract
The green sulfur bacterium Chlorobium tepidum contains bacteriochlorophyll (BChl) aP and chlorophyll (Chl) aPD as minor chlorophyllous components as well as major BChl c. BChl aP acts as antenna pigments and P840, and Chl aPD serves as a primary acceptor in the reaction center. The former pigment possesses a phytyl group on the C-17 position, while the latter is esterified with delta-2,6-phytadienol. Although it is known that both long hydrocarbon chains are synthesized from a geranylgeranyl group by geranylgeranyl reductase, CT2256, it is not still revealed that why CT2256 synthesizes different long hydrocarbon chains in BChl aP and Chl aPD. To clarify the reaction process of CT2256, we constructed mutants of Chlorobium tepidum, that were deleted CT2256 gene, and then introduced either cyanobacterial chlP gene or purple bacterial bchP gene. We will discuss the reduction process of CT2256 from results of pigments analysis of above mutants.
