title: In Vitro Enzymatic Activities of Bacteriochlorophyll a Synthase Derived from the Green Sulfur Photosynthetic Bacterium Chlorobaculum tepidum.
abstract: The activity of an enzyme encoded by the CT1610 gene in the green sulfur photosynthetic bacterium Chlorobaculum tepidum, which was annotated as bacteriochlorophyll (BChl) a synthase, BchG (denoted as tepBchG), was examined in vitro using the lysates of Escherichia coli containing the heterologously expressed enzyme. BChl a possessing a geranylgeranyl group at the 17-propionate residue (BChl aGG) was produced from bacteriochlorophyllide (BChlide) a and geranylgeranyl pyrophosphate in the presence of tepBchG. Surprisingly, tepBchG catalyzed the formation of BChl a bearing a farnesyl group (BChl aF) as in the enzymatic production of BChl aGG, indicating loose recognition of isoprenoid pyrophosphates in tepBchG. In contrast to such loose recognition of isoprenoid substrates, BChlide c and chlorophyllide a gave no esterifying product upon being incubated with geranylgeranyl or farnesyl pyrophosphate in the presence of tepBchG. These results confirm that tepBchG undoubtedly acts as the BChl a synthase in Cba. tepidum. The enzymatic activity of tepBchG was higher than that of BchG of Rhodobacter sphaeroides at 45 °C, although the former activity was lower than the latter below 35 °C.
authors.affiliation: †Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan.|‡PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Saga
authors.affiliation: †Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan.
authors.forename: Keiya
authors.initials: K
authors.lastname: Hirota
authors.affiliation: §Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka 830-0011, Japan.
authors.forename: Jiro
authors.initials: J
authors.lastname: Harada
authors.affiliation: ∥Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Tamiaki
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D025541:Bacteriochlorophyll A / Q000096:biosynthesis / Q000737:chemistry; D019729:Carbon-Oxygen Ligases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019414:Chlorobi / Q000201:enzymology* / Q000235:genetics; D005798:Genes, Bacterial; D015394:Molecular Structure; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012242:Rhodobacter sphaeroides / Q000201:enzymology; D013045:Species Specificity; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D025541:Bacteriochlorophyll A; D011994:Recombinant Proteins; D019729:Carbon-Oxygen Ligases; C105512:bacteriochlorophyll a synthase