DNA binding of citrus dehydrin promoted by zinc ion.

HARA, MASAKAZU; SHINODA, YURI; TANAKA, YASUTAKA; KUBOI, TORU

Dehydrins are hydrophilic proteins that accumulate during embryogenesis and osmotic stress responses in plants. Here, we report an interaction between citrus dehydrin Citrus unshiu cold-regulated 15 kDa protein (CuCOR15) and DNA. Binding of CuCOR15 to DNA was detected by an electrophoretic mobility shift assay, a filter-binding assay and Southwestern blotting. The binding was stimulated by physiological concentrations of Zn2 , but little stimulation occurred when other divalent cations, such as Mg2 , Ca2 , Mn2 , Ni2 and Cu2 , were substituted for Zn2 . Ethylenediaminetetraacetic acid cancelled the Zn2 -stimulated binding. A binding curve and competitor experiments suggested that the DNA binding of CuCOR15 exhibited low affinity and non-specificity. Moreover, tRNA competed with the DNA binding. Histidine-rich domains and a polylysine segment-containing domain participated in the DNA binding. These results suggest that CuCOR15 can interact with DNA, and also RNA, in the presence of Zn2 . Dehydrin may protect nucleic acids in plant cells during seed maturation and stress responses.

NUCLEIC acids; DNA; ZINC; ACETIC acid; ETHYLENEDIAMINETETRAACETIC acid; OSMOREGULATION

Plant, Cell & Environment, 2009, Vol 32, Issue 5, p532

0140-7791

Academic Journal

10.1111/j.1365-3040.2009.01947.x