电力工业部令.doc

Binding to the Minor Groove of the Double-Strand, Tau
Protein Prevents DNA from Damage by Peroxidation
. .
Yan Wei1,2 , Mei-Hua Qu1 , Xing-Sheng Wang1, Lan Chen1, Dong-Liang Wang1,2, Ying Liu1, Qian Hua1,3,
Rong-Qiao He1,2*
1 State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China, 2 Graduate University of Chinese Academy of
Sciences, Beijing, China, 3 School of Preclinical Medicine, Beijing University of Chinese Medicine, Beijing, China
Abstract
Tau, an important microtubule associated protein, has been found to bind to DNA, and to be localized in the nuclei of both
neurons and some non-neuronal cells. Here, using electrophoretic mobility shifting assay (EMSA) in the presence of DNA
with different chain-lengths, we observed that tau protein favored binding to a 13 bp or a longer polynucleotide. The
results from atomic force microscopy also showed that tau protein preferred a 13 bp polynucleotide to a 12 bp or shorter
polynucleotide. In petitive assay, a minor groove binder distamycin A was able to replace the bound tau from the
DNA double helix, indicating that tau protein binds to the minor groove. Tau protein was able to protect the double-strand
from digestion in the presence of DNase I that was bound to the minor groove. On the other hand, a major groove binder
methyl green as a petitor exhibited little effect on the retardation of tau-plex in EMSA. This further
indicates the DNA minor groove as the binding site for tau protein. EMSA with truncated tau proteins showed that both the
proline-rich domain (PRD) and the microtubule-binding domain (MTBD) contributed to the interaction with DNA; that is to
say, both PRD and MTBD bound to the minor groove of DNA and bent the double-strand, as observed by electron
microscopy. To investigate whether tau protein is able to prevent DNA from the impairment by hydroxyl free radical, the
chemiluminescence emitted by the phen-C