A GLOBAL PROFILE OF YEAST GENES INVOLVED IN AGROBACTERIUM- YEAST GENE TRANFER

Abstract

Agrobacterium tumefaciens can transfer a piece of DNA (T-DNA) into natural host plant cells as well as a wide range of laboratory hosts of eukaryotic cells, including Saccharomyces cerevisiae. Many of the A. tumefaciens factors involved in the process have been well characterized. However, much remains unknown about the host genes and factors involved in T-DNA transfer.

In the current project, a novel system has been developed that can rapidly identify S. cerevisiae genes involved in the Agrobacterium-yeast gene transfer. Using this system, we screened the entire yeast knock-out mutant library and identified 209 yeast genes that are important for the T-DNA transfer. Mutations at some of these genes reduced the transformation efficiencies dramatically, while mutations at other increased the efficiencies significantly. The studies revealed for the first time that several host processes such as TCA cycle and posttranslational modifications are involved in Agrobacterium-yeast gene transfer pathways. In particular, the glycosylation pathway components like the OST3 gene and the components of oligosaccharyltransferase (OST) complex positively regulate the Agrobacterium-mediated transformation (AMT) process. Some of the OST3 downstream glycoproteins were also found to be involved in the AMT process. The global profile of the yeast genes involved in the AMT process facilitates a systemic approach to explore the molecular events involved in the process.