A bacterial peptide acting as a plant nuclear targeting signal: the amino-terminal portion of Agrobacterium VirD2 protein directs a beta-galactosidase fusion protein into tobacco nuclei.
Agrobacterium tumefaciens is a soil bacterium capable of transferring DNA to the genome of higher plants. Of the virulence region-encoded proteins of the tumor-inducing (Ti) plasmid of A. tumefaciens, the VirD1 and VirD2 proteins are essential for T-DNA transfer to plant cells. These two proteins have been shown to be directly responsible for the formation of T-strands. VirD2 was also shown to be firmly attached to the 5' termini of T-strands; these facts have led to its postulation as a pilot protein in the T-DNA transfer process and as a nucleus-targeting signal in plants. We have constructed a chimeric gene by fusing the virD2 gene and the Escherichia coli lacZ gene. Cell fractionation and electron microscopy studies with transgenic tobacco plants containing the VirD2-LacZ fusion protein indicate that the first 292 amino acids of VirD2 are able to direct the cytoplasmic protein beta-galactosidase to the plant nucleus. This provides an example of cross-kingdom nuclear localization between two free-living organisms: a bacterial peptide is capable of acting as a eukaryotic (plant) nuclear targeting signal.
Herrera-Estrella
A
A
Laboratorium voor Genetica, Rijksuniversiteit Gent, Belgium.
Van Montagu
M
M
Wang
K
K
D001426:Bacterial Proteins / Q000235:genetics*; D002467:Cell Nucleus / Q000378:metabolism; D007700:Kinetics; D008854:Microscopy, Electron; D010947:Plants, Toxic; D011993:Recombinant Fusion Proteins / Q000378:metabolism / Q000648:ultrastructure; D012231:Rhizobium / Q000235:genetics* / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*; D037521:Virulence Factors; D001616:beta-Galactosidase / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure
D001426:Bacterial Proteins; D011993:Recombinant Fusion Proteins; D037521:Virulence Factors; D001616:beta-Galactosidase