Difference between revisions of "Part:BBa K2433000"

Revision as of 05:19, 1 November 2017

ietA

ietA is the gene encoding the antitoxin in the toxin antitoxin system ietAS native to tumor-inducing (Ti) plasmids of Agrobacterium tumefaciens. The ietAS operon was given its name after the incompatibility enhancer of the Ti plasmid. This part comes from the nopaline type Ti plasmid pTiC58. In combination with the toxin gene, this part has been shown in literature to be important in reducing the transconjugant efficiency for different incoming Ti plasmids as well as contributing to the stability of plasmids harboring this construct.

Data base searches have shown that IetA is similar in structure to AAA-ATPases. IetA is considered to be a type II antitoxin, which are small, unstable proteins. While unstable, antitoxins are expressed at higher levels than their cognate toxins. The antitoxin neutralizes the effect of the toxin on the host cell by forming a protein complex.

When a plasmid loses its toxin/antitoxin construct, antitoxin levels become depleted due to rapid degradation by proteases. This enables the toxin to exert its toxicity on the host cell, inhibiting growth. Hence, the survival of cells containing the ietAS system is dependant on the presence and functionality of the ietA.

ietAS was shown to enhance the incompatibility and stability of the Ti plasmid in Agrobacterium tumefaciens, however, the presence of ietAS showed no effect when tested in E. coli. (Yamamoto et al., 2009)

References
Melderen, L. V., & Bast, M. S. (2009). Bacterial Toxin–Antitoxin Systems: More Than Selfish Entities? PLoS Genetics, 5(3). doi:10.1371/journal.pgen.1000437
Unterholzner, S. J., Poppenberger, B., & Rozhon, W. (2013). Toxin–antitoxin systems: Biology, identification, and application. Mobile Genetic Elements, 3(5), e26219. http://doi.org/10.4161/mge.26219
Yamamoto, S., Kiyokawa, K., Tanaka, K., Moriguchi, K., & Suzuki, K. (2009). Novel Toxin-Antitoxin System Composed of Serine Protease and AAA-ATPase Homologues Determines the High Level of Stability and Incompatibility of the Tumor-Inducing Plasmid pTiC58. Journal of Bacteriology, 191(14), 4656-4666. doi:10.1128/jb.00124-09

Sequence and Features