Evidence that ubiquinone is a required intermediate for rhodoquinone biosynthesis in Rhodospirillum rubrum.
Rhodoquinone (RQ) is an important cofactor used in the anaerobic energy metabolism of Rhodospirillum rubrum. RQ is structurally similar to ubiquinone (coenzyme Q or Q), a polyprenylated benzoquinone used in the aerobic respiratory chain. RQ is also found in several eukaryotic species that utilize a fumarate reductase pathway for anaerobic respiration, an important example being the parasitic helminths. RQ is not found in humans or other mammals, and therefore inhibition of its biosynthesis may provide a parasite-specific drug target. In this report, we describe several in vivo feeding experiments with R. rubrum used for the identification of RQ biosynthetic intermediates. Cultures of R. rubrum were grown in the presence of synthetic analogs of ubiquinone and the known Q biosynthetic precursors demethylubiquinone, demethoxyubiquinone, and demethyldemethoxyubiquinone, and assays were monitored for the formation of RQ(3). Data from time course experiments and S-adenosyl-l-methionine-dependent O-methyltransferase inhibition studies are discussed. Based on the results presented, we have demonstrated that Q is a required intermediate for the biosynthesis of RQ in R. rubrum.
Brajcich
Brian C
BC
Department of Chemistry and Biochemistry, Gonzaga University, Spokane, WA 99258-0005, USA.
Iarocci
Andrew L
AL
Johnstone
Lindsey A G
LA
Morgan
Rory K
RK
Lonjers
Zachary T
ZT
Hotchko
Matthew J
MJ
Muhs
Jordan D
JD
Kieffer
Amanda
A
Reynolds
Bree J
BJ
Mandel
Sarah M
SM
Marbois
Beth N
BN
Clarke
Catherine F
CF
Shepherd
Jennifer N
JN
D002853:Chromatography, Liquid; D013058:Mass Spectrometry; D008954:Models, Biological; D015394:Molecular Structure; D012247:Rhodospirillum rubrum / Q000378:metabolism*; D014451:Ubiquinone / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*
D014451:Ubiquinone; C003304:rhodoquinone