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Pilus assembly by Agrobacterium T-DNA transfer genes
K J Fullner1, J C Lara, E W Nester
1Department of Microbiology, University of Washington, Seattle, WA 98195-7242, USA.
Science (New York, N.Y.)
|August 23, 1996
Summary
Agrobacterium tumefaciens uses pili for transferring DNA to plant cells. Pilus formation requires specific virulence genes and low temperatures, essential for genetic transformation.
Area of Science:
- Molecular biology
- Microbiology
- Plant pathology
Background:
- Agrobacterium tumefaciens is a plant pathogen that genetically transforms eukaryotic cells.
- Bacterial pili are known to mediate interbacterial DNA transfer.
- Pilus formation in Agrobacterium is linked to the expression of virulence genes.
Purpose of the Study:
- To investigate the role of pili in Agrobacterium tumefaciens DNA transfer to plant cells.
- To identify the specific genes involved in pilus assembly and function.
- To elucidate the mechanism of DNA transfer mediated by Agrobacterium pili.
Main Methods:
- Genetic analysis of Agrobacterium tumefaciens mutants.
- Assaying pilus formation under various growth conditions.
- Correlating pilus presence/absence with DNA transfer efficiency.
Main Results:
- Pilus formation requires induction of tumor-inducing (Ti) plasmid virulence genes and low-temperature growth.
- Virulence genes virA, virG, virB1-virB11, and virD4 are essential for pilus assembly.
- Loss of pili correlated with loss of transferred DNA (T-DNA) transfer, and vice versa.
Conclusions:
- Agrobacterium pili are essential for the transfer of T-DNA to plant cells.
- The process of DNA transfer mediated by pili resembles bacterial conjugation.
- Understanding pilus function is key to harnessing Agrobacterium for genetic transformation.