Use of SUP-TALs to suppress virulence factors in Xanthomonas BLS256

Project Summary

The bacterial plant pathogen Xanthomonas causes devastating disease on various plant species such as rice and soybeans, which results in bacterial infections such as bacterial leaf streaks. Many species of Xanthomonas rely on a delivery of transcription activator like (TAL) Effectors to host plant cells in order to cause disease. TALEs travel to the nucleus where they then bind to a specific section of DNA and up regulate expression of downstream genes. The TALE DNA binding code is predictable, which makes it possible to build designer TALEs(dTALs) to target any gene of interest. Recently, a group of synthetic biologist expressed dTALs in E. coli targeting the E. coli genome and saw that the dTALs acted as gene repressors. Because dTALs work as suppressors of gene activity in prokaryotes, we refer to them as suppressor TALs, or SUP-TALs. We wanted to see if SUP-TALs would behave in a similar manner in Xanthomonas, where they could possibly be used to probe virulence functions of targeted genes. For my project SUP-TALs were designed and made to target xanB in Xanthomonas BLS256. The xanB gene is known to be responsible for the quorum sensing of both Xanthomonadins and EPS production. Because xanB is located in an operon with xanA, four SUP-TALs were made to target the xanA promoter and two SUP-TALs were made to target the xanB promoter region. If any of these SUP-TALs are successful, we should see reduced expression of xanB and less Xanthomonadin and EPS production. We saw significant differences in growth between Xanthomonas BLS256 transformed with pAC99, and the Xanthomonas BLS256 transformed with the SUP-TALs. SUP-TALs may be an efficient tool for suppressing genes to see their function. It could be particularly useful for targeting genes which are typically knocked out with the use of traditional methods.

My Experience

My time spent in the Bogdanove lab is one for the memory books. I’ve met so many incredible faculty, researchers, and undergraduate students, and have learned more in this short time than I ever thought possible.  I’ve learned a variety of microbiology lab procedures, and techniques such as Gateway cloning, bacterial transformations, qPCR, and many more. From this internship I have gained confidence in my research abilities and I am hoping to continue the research I began this summer. The BTI internship did an excellent job of depicting what graduate school would be like in plant biology. The internship also did a wonderful job of demonstrating the diversity in plant biology and the various careers you could enter after graduate school. Coming into this internship I was set on going to medical school. After completing the internship I’ve decided that I will be going to graduate school, most likely in a plant biology field.