The VirD2 protein of A. tumefaciens contains a C-terminal bipartite nuclear localization signal: implications for nuclear uptake of DNA in plant cells.
Here we show that the VirD2 protein of A. tumefaciens functions as a nuclear localizing protein in plant cells. The nuclear localization signal of VirD2 consists of two regions containing 4-5 basic amino acids (KRPR and RKRER), located within the C-terminal 34 amino acids. These regions conform to the KR/KXR/K motif required for numerous nuclear localized nonplant eukaryotic proteins. Each region independently directs a beta-glucuronidase reporter protein to the nucleus; however, both regions are necessary for maximum efficiency. VirD2 has been shown to be tightly bound to the 5' end of the single-stranded DNA transfer intermediate, T-strand, transferred from Agrobacterium to the plant cell genome. The present results imply that T-strand transport to the plant nucleus is mediated by the tightly attached VirD2 protein via an import pathway common to higher eukaryotes.
Howard
E A
EA
Department of Plant Biology, University of California-Berkeley 94720.
Zupan
J R
JR
Citovsky
V
V
Zambryski
P C
PC
D016960:Agrobacterium tumefaciens / Q000235:genetics / Q000502:physiology*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D002467:Cell Nucleus / Q000502:physiology*; D002478:Cells, Cultured; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010947:Plants, Toxic; D010957:Plasmids; D021382:Protein Sorting Signals / Q000235:genetics*; D011523:Protoplasts / Q000502:physiology; D012689:Sequence Homology, Nucleic Acid; D014026:Nicotiana / Q000382:microbiology*; D037521:Virulence Factors
D001426:Bacterial Proteins; D021382:Protein Sorting Signals; D037521:Virulence Factors