Abstract
Methylated-DNA binding domain proteins (MBD proteins) recognize 5-methylcytosine in genomic DNA, and generally repress gene expression. Searching for proteins that interact with an Arabidopsis MBD protein, AtMBD5, we identified a small GTPase AtRan3 by the yeast two-hybrid screening.
The pull down assay using bacterially expressed proteins confirmed the interaction between AtMBD5 and AtRan3. The GTP-bound form of AtRan3 interacted more efficiently than the GDP-bound form. Both AtMBD5 and AtRan3 were ubiquitously expressed in Arabidopsis tissues, particularly high in flower. Since ran GTPases are known to be involved in mammalian cell division, each gene was transformed into tobacco BY2 cells as fluorescence fusion proteins, and their cellular localization was observed during cell cycle. The localization of AtMBD5 coincided with that of AtRan3 during prophase, metaphase and anaphase. These results suggested that AtMBD5 and AtRan3 form a complex, which possibly plays an important role during the cell division of plant cell.
