Specific Gene bciD for C7-Methyl Oxidation in Bacteriochlorophyll e Biosynthesis of Brown-Colored Green Sulfur Bacteria

The gene named bciD, which encodes the enzyme involved in C7-formylation in bacteriochlorophyll e biosynthesis, was found and investigated by insertional inactivation in the brown-colored green sulfur bacterium Chlorobaculum limnaeum (previously called Chlorobium phaeobacteroides). The bciD mutant cells were green in color, and accumulated bacteriochlorophyll c homologs bearing the 7-methyl group, compared to C7-formylated BChl e homologs in the wild type. BChl-c homolog compositions in the mutant were further different from those in Chlorobaculum tepidum which originally produced BChl c: (31S)-8-isobutyl-12-ethyl-BChl c was unusually predominant.研究人员通过插入失活（insertional inactivation）技术，在棕色绿色硫细菌湖生绿杆菌（Chlorobaculum limnaeum，曾被命名为褐色绿菌Chlorobium phaeobacteroides）中发现并研究了编码参与细菌叶绿素e（bacteriochlorophyll e）生物合成过程中C7-甲酰化（C7-formylation）反应的酶的bciD基因。与野生型中带有C7-甲酰化修饰的细菌叶绿素e同系物相比，该bciD突变菌株呈绿色，并积累了带有7-甲基基团的细菌叶绿素c（bacteriochlorophyll c，BChl c）同系物。该突变体的细菌叶绿素c同系物组成与原本合成细菌叶绿素c的嗜热绿杆菌（Chlorobaculum tepidum）相比存在进一步差异：(31S)-8-异丁基-12-乙基-细菌叶绿素c（(31S)-8-isobutyl-12-ethyl-BChl c）异常富集。