Dual Functions of the KNOTTED1 Homeodomain: Sequence-Specific DNA Binding and Regulation of Cell-to-Cell Transport
Nathalie Bolduc1,
Sarah Hake1, and
David Jackson2*
1Plant Gene Expression Center, 800 Buchanan Street, Albany, CA 94710, USA.
2Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
Abstract:
Homeodomain proteins are well-characterized developmental regulators that control expression of target genes through sequence-specific DNA binding. The homeodomain forms a trihelical structure, with the third helix conferring specific interactions with the DNA major groove. A specific class of plant homeodomain proteins, called KNOX [KNOTTED1 (KN1)-like homeobox], also has the ability to signal between cells by directly trafficking through intercellular channels called plasmodesmata. Trafficking is mediated by a signal that is also contained within the homeodomain. Movement protein binding protein 2C was identified as a protein that interacts with the KN1 homeodomain and regulates the cell-to-cell trafficking of KN1 by sequestering the protein on microtubules. Therefore, KN1 has multiple potential cellular addresses, each of which is conferred by its homeodomain.
*Corresponding author. E-mail: jacksond{at}cshl.edu
