Determining the Rhodoquinone Biosynthetic Pathway in Rhodospirillum rubrum Using Gene Knock‐outs

Many parasitic helminths require the metabolic cofactor rhodoquinone (RQ) for anaerobic respiration. Inhibition of RQ biosynthesis may shut down the anaerobic respiration pathway and provide a new target for anti‐helminthic drug design. The bacteria Rhodospirillum rubrum (R. rubrum) is a good model organism for RQ biosynthesis because it utilizes the same respiration pathway as the helminths when grown under anaerobic conditions. Previous studies have shown that ubiquinone (Q) is a required precursor to RQ in R. rubrum , and that the gene, rquA , is required for this conversion. Since this process likely requires additional enzymes, further investigation has identified potential gene targets within the R. rubrum genome that may be involved in the pathway. This project involved completing a collection of knockout mutant strains , with the deletion of ten genes from the R. rubrum genome that are hypothesized to be involved in the RQ biosynthetic pathway. RQ production was analyzed using liquid chromatography mass spectroscopy in each of the mutant strains, alongside wild type. The gene expression of rquA was also monitored using real‐time quantitative PCR. Support or Funding Information National Institutes of Health (1R15GM096398‐01) and Howard Hughes Medical Institute (award to Gonzaga University).