title: A seventh bacterial chlorophyll driving a large light-harvesting antenna.
abstract: 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.
authors.affiliation: Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, Japan. jiro_harada@med.kurume-u.ac.jp
authors.forename: Jiro
authors.initials: J
authors.lastname: Harada
authors.forename: Tadashi
authors.initials: T
authors.lastname: Mizoguchi
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Tsukatani
authors.forename: Masato
authors.initials: M
authors.lastname: Noguchi
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Tamiaki
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D001429:Bacteriochlorophylls / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D019414:Chlorobi / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D055786:Gene Knockout Techniques; D005798:Genes, Bacterial; D008780:Methyltransferases / Q000235:genetics; D010788:Photosynthesis; D052979:Phycobiliproteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet
chemical_list: D001426:Bacterial Proteins; D001429:Bacteriochlorophylls; D052979:Phycobiliproteins; D008780:Methyltransferases