Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, Japan.
Sci Rep. 2012;2:671. doi: 10.1038/srep00671. Epub 2012 Sep 19.
The discovery of new chlorophyllous pigments would provide greater understanding of the mechanisms and evolution of photosynthesis. Bacteriochlorophyll f has never been observed in nature, although this name was proposed 40 years ago based on structurally related compounds. We constructed a bacteriochlorophyll f-accumulating mutant of the green sulfur bacterium Chlorobaculum limnaeum, which originally produced bacteriochlorophyll e, by knocking out the bchU gene encoding C-20 methyltransferase based on natural transformation. This novel pigment self-aggregates in an in vivo light-harvesting antenna, the chlorosome, and exhibits a Q(y) peak of 705 nm, more blue-shifted than any other chlorosome reported so far; the peak overlaps the maximum (700 nm) of the solar photon flux spectrum. Bacteriochlorophyll f chlorosomes can transfer light energy from core aggregated pigments to another bacteriochlorophyll in the chlorosomal envelope across an energy gap of ~100 nm, and is thus a promising material for development of new bioenergy applications.
发现新的叶绿素色素将有助于更好地理解光合作用的机制和进化。尽管大约 40 年前就根据结构相关的化合物提出了菌绿素 f 的名称，但在自然界中从未观察到过这种物质。我们通过基于自然转化的基因敲除，构建了一种原本产生菌绿素 e 的绿硫细菌 Chlorobaculum limnaeum 的菌绿素 f 积累突变体。这种新型色素在体内光收集天线——类菌胞体中自行聚集，并表现出 705nm 的 Q(y)峰，比迄今为止报道的任何其他类菌胞体都更蓝移；该峰与太阳光子通量光谱的最大值（约 700nm）重叠。菌绿素 f 类菌胞体可以在约 100nm 的能量间隙内，将核心聚集色素的光能从一个菌绿素转移到类菌胞体包膜中的另一个菌绿素，因此是开发新生物能源应用的有前途的材料。
