In Vitro Enzymatic Activities of Bacteriochlorophyll a Synthase Derived from the Green Sulfur Photosynthetic Bacterium Chlorobaculum tepidum

Biochemistry. 2015 Aug 18;54(32):4998-5005. doi: 10.1021/acs.biochem.5b00311. Epub 2015 Aug 10.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Bacteriochlorophyll A / biosynthesis
  • Bacteriochlorophyll A / chemistry
  • Carbon-Oxygen Ligases / chemistry
  • Carbon-Oxygen Ligases / genetics
  • Carbon-Oxygen Ligases / metabolism*
  • Chlorobi / enzymology*
  • Chlorobi / genetics
  • Genes, Bacterial
  • Molecular Structure
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Rhodobacter sphaeroides / enzymology
  • Species Specificity
  • Substrate Specificity


  • Bacterial Proteins
  • Bacteriochlorophyll A
  • Recombinant Proteins
  • Carbon-Oxygen Ligases
  • bacteriochlorophyll a synthase