THE PLANT CELL, Vol 5, Issue 8 983-994, Copyright © 1993 by American Society of Plant Biologists
Specific Binding of Nuclear Localization Sequences to Plant Nuclei
G. R. Hicks and N. V. Raikhel
Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824-1312
We have begun to dissect the import apparatus of higher plants by examining
the specific association of nuclear localization sequences (NLSs) with
purified plant nuclei. Peptides to the simian virus 40 (SV40) large T
antigen NLS and a bipartite NLS of maize were allowed to associate with
tobacco and maize nuclei. Wild-type NLSs were found to compete for a single
class of low-affinity binding sites having a dissociation constant (Kd) of
~200 [mu]M. Peptides to mutant NLSs, which are inefficient in stimulating
import, were poor competitors, as were reverse wild-type and non-NLS
peptides. The NLS binding site was proteinaceous and resistant to
extraction under conditions where pores were still associated. In addition,
immunofluorescence and immunoelectron microscopy indicated that binding was
at the nuclear envelope. Overall, plant nuclei may be an excellent system
to identify components of the import apparatus.
