ATP-induced shrinkage of DNA with MukB protein and MukBEF complex of Escherichia coli

Department of Physics, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan and Spatio-Temporal Order Project, ICORP, JST, Japan; Graduate School of Environmental Studies, Nagoya University, Nagoya, 464-8601, Japan; Faculty of Education for Future Generations, International Pacific University, Okayama 709-0863, Japan; Department of Radiation Genetics, Graduate School of Medicine, 606-8502, Kyoto University, Kyoto, Japan; Radiation Laboratory Center, Wakayama Medical University, School of Medicine, 811-1, Kimiidera, Wakayama 641-8509, Japan

^* To whom correspondence should be addressed. Email: yoshikaw{at}scphys.kyoto-u.ac.jp.

	Abstract

Fluorescence microscopic observation on individual T4 DNA molecules revealed that MukBEF complex (bacterial condensin) and its subunit MukB (a member of SMC superfamily) homodimer of Escherichia coli shrunk markedly large DNA molecules in the presence of hydrolysable ATP. Contrary, in the presence of ADP or ATP-S, the conformation of DNA was almost not changed. This suggests that the ATPase activity of subunit MukB is essential to shrink large DNA molecules. Stretching experiment on the shrunken DNA in the presence of ATP and MukBEF indicated cross bridging interaction between DNA molecules.