Intellectual Merit. Gene flow between species is a natural process. The ubiquitous soil bacteria Agrobacterium tumefaciens and A. rhizogenes naturally transfer some of their DNA to plants, leading to production of crown gall and hairy root diseases. This ability to transfer DNA has been exploited for genetic engineering and is now the preferred method for delivering genes to plant cells. Despite the widespread use, many mechanistic questions remain about how the gene transfer takes place. In A. tumefaciens, the VirE2 protein plays a major role by coating the transferred DNA and facilitating its uptake into the nucleus of the plant cell. However, this does not appear to be a universal mechanism, as some strains of A. rhizogenes transfer DNA efficiently, but lack VirE2. Instead, these strains contain another protein, GALLS, that can substitute for VirE2, thus providing an alternate route for nuclear uptake of transferred DNA. Apparently, upon entry into plant cells, GALLS localizes inside the nucleus where it interacts with a bacterial pilot protein attached to the transferred DNA and with a plant protein (GALLS-Interacting Protein; GIP). GALLS is hypothesized to act as a "molecular tractor" to pull transferred DNA into the nucleus. To test this idea, multiple experimental approaches will be used to understand how GALLS and GIP promote gene transfer via a VirE2-independent pathway.
Broader Impacts. These studies will increase understanding of Agrobacterium-mediated gene transfer and identify additional unknown components of this extremely important gene delivery system. This project will promote education and training of a doctoral student at Oregon State University and a postdoctoral associate at Purdue University. In addition, minority undergraduates from Brooklyn College will be recruited to participate in summer research internships at Purdue. After their summer experiences, the students will continue to engage in related hands-on research at their home institution.
