Biosynthesis of bacteriochlorophyll c derivatives possessing chlorine and bromine atoms at the terminus of esterifying chains in the green sulfur bacterium Chlorobaculum tepidum.
The green sulfur photosynthetic bacterium Chlorobaculum tepidum newly produced BChl c derivatives possessing a chlorine or bromine atom at the terminus of the esterifying chain in the 17-propionate residue by cultivation with exogenous ω-halo-1-alkanols. The relative ratios of BChl c derivatives esterified with 8-chloro-1-octanol and 10-chloro-1-decanol were estimated to be 26.5% and 33.3% by cultivation with these ω-chloro-1-alkanols at the final concentrations of 300 and 150 μM, respectively. In contrast, smaller amounts of unnatural BChls c esterified with ω-bromo-1-alkanols were biosynthesized than those esterified with ω-chloro-1-alkanols: the ratios of BChl c derivatives esterified with 8-bromo-1-octanol and 10-bromo-1-decanol were 11.3% and 12.2% at the concentrations of 300 and 150 μM, respectively. These indicate that ω-chloro-1-alkanols can be incorporated into bacteriochlorophyllide c more than ω-bromo-1-alkanols in the BChl c biosynthetic pathway. The homolog compositions of the novel BChl c derivatives possessing a halogen atom were analogous to those of coexisting natural BChl c esterified with farnesol. These results demonstrate unique properties of BChl c synthase, BchK, which can utilize unnatural substrates containing halogen in the BChl c biosynthesis of Cba. tepidum.
Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan. Electronic address: saga@chem.kindai.ac.jp.
Yoshitaka
Y
Saga
Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan.
Keisuke
K
Hayashi
Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
Tadashi
T
Mizoguchi
Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
Hitoshi
H
Tamiaki
D001426:Bacterial Proteins / Q000737:chemistry*; D001429:Bacteriochlorophylls / Q000096:biosynthesis* / Q000737:chemistry; D001966:Bromine / Q000032:analysis; D002713:Chlorine / Q000032:analysis; D019414:Chlorobi / Q000737:chemistry / Q000378:metabolism*; D004951:Esterification
D001426:Bacterial Proteins; D001429:Bacteriochlorophylls; D002713:Chlorine; C002084:bacteriochlorophyll c; D001966:Bromine
Bacteriochlorophyll; Biosynthesis; Chlorosome; Green photosynthetic bacteria; Photosynthesis