The Regulation of Bacteriochlorophyll Synthesis in Rhodobacter Capsulatus

Abstract

As members of the genus Rhodobacter respond to shifting environmental conditions, the amount and composition of the photosynthetic apparatus changes. The photosynthetic apparatus is composed of specific complexes of proteins and photosynthetic pigments, and the changes in the photosynthetic apparatus are achieved in a coordinated fashion so that neither pigment nor protein is accumulated in excess. It is especially important that neither bacteriochlorophyll (BChl) nor its precursors accumulate in excess, since these compounds are sensitizers to photo-dynamic killing processes. We have discovered a protein,thee product of the pufQ gene, that mediates the coordination between pigment and protein synthesis. In the course of studying how this coordination of syntheses is achieved, we have found an unusual superoperonal arrangement of the genes coding for various elements of the photosynthetic apparatus.