Journal
JOURNAL OF THE KOREAN SOCIETY FOR APPLIED BIOLOGICAL CHEMISTRY
Volume 58, Issue 6, Pages 877-885Publisher
KOREAN SOC APPLIED BIOLOGICAL CHEMISTRY
DOI: 10.1007/s13765-015-0116-9
Keywords
Burkholderia glumae; GTP cyclohydrolase II; ribA; toxB; Toxoflavin
Categories
Funding
- Myongji University
Ask authors/readers for more resources
Burkholderia glumae synthesizes toxoflavin, a phytotoxin that contributes the virulence of this phytopathogen. The toxoflavin biosynthetic gene cluster contains a tox operon composed of five genes, toxABCDE, and toxB is predicted to encode a GTP cyclohydrolase II, which is the first enzyme (RibA) in riboflavin biosynthesis. ToxE is also homologous to RibD, the bifunctional deaminase/reductase acting on the RibA product. This suggests that toxoflavin and riboflavin biosynthesis share the first two steps in their respective biosyntheses. In this study, we demonstrated that ToxB and B. glumae RibA (Bglu-RibA) both displayed GTP cyclohydrolase II activity with comparable kinetic parameters. When toxB was inactivated, toxoflavin production was abolished, and introduction of a plasmid copy of Bglu-ribA restored toxoflavin production in a Delta toxB mutant. ToxB and Bglu-RibA can thus be defined as GTP cyclohydrolase II isozymes, even though Bglu-ribA is not a genetic equivalent of toxB because the chromosomal copy of Bglu-ribA is unable to support toxoflavin production in the absence of toxB. In LB agar culture, toxAB is incapable of complementing Delta toxB though toxABC induced toxoflavin accumulation in the Delta toxB mutant up to 80 % of the WT level. This indicates that toxBC co-expression is a critical factor for toxoflavin biosynthesis in this condition, suggesting that the WD repeat protein ToxC acts as a scaffolding protein in a toxoflavin biosynthetic metabolon. In LB liquid culture, toxAB successfully restored toxoflavin production, suggesting that a role of toxBC co-expression is dependent upon growth condition.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available