The basic domain of plant B-ZIP proteins facilitates import of a reporter protein into plant nuclei.
The import of large molecules into the nucleus is an active process that requires the presence in cis of a nuclear localization signal (NLS). Although these signals have been well characterized in mammalian, yeast, and amphibian nuclear proteins, no plant NLS has yet been described. The NLSs identified so far generally contain clusters of basic amino acids. This characteristic feature prompted us to test several basic domains from the plant DNA-binding proteins TGA-1A and TGA-1B and the TATA box-binding protein TFIID for nuclear targeting function. When tested as N-terminal fusions to the beta-glucuronidase protein, only those constructs containing the DNA binding (basic) domain of the basic-zipper (B-ZIP) region of TGA-1A or TGA-1B conferred nuclear import. These results suggest a close association or overlap of the DNA binding and nuclear targeting domains of B-ZIP proteins. We also demonstrated that a wild-type but not a mutant simian virus 40 large T-antigen NLS facilitates import into plant nuclei, indicating a strong conservation between nuclear import mechanisms in animals and plants.
van der Krol
A R
AR
Laboratory of Plant Molecular Biology, Rockefeller University, New York, New York 10021.
Chua
N H
NH
D000595:Amino Acid Sequence; D000957:Antigens, Viral, Tumor / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001692:Biological Transport; D002467:Cell Nucleus / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005814:Genes, Viral / Q000235:genetics; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D021382:Protein Sorting Signals / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D000957:Antigens, Viral, Tumor; D004268:DNA-Binding Proteins; D010940:Plant Proteins; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; D005966:Glucuronidase