Localization of Linker Histone in Chromatosomes by Cryo-Atomic Force Microscopy
Sitong Sheng 1, Daniel Czajkowsky 2 and Zhifeng Shao 1*
1 University of Virginia School of Medicine
2 University of Virginia
* To whom correspondence should be addressed. E-mail: zs9q{at}virginia.edu.
Submitted on June 1, 2006
Revised on June 9, 2006
Accepted on 9 June 2006
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Abstract |
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Linker histones play a fundamental role in determining higher order chromatin structure as a consequence of their association with nucelosomal DNA. Yet the locations and structural consequences of linker histone binding are still enigmatic. Here, using cryo-atomic force microscopy, we show that the linker histone H5 in native chromatin and in chromatosomes reconstituted on the 5S rDNA template is located at the dyad of the nucleosome core particle, within the "stem" structure. Direct measurement also indicates that the length of free linker DNA between chromatosomes in native chromatin is ~30 bp, slightly shorter than that estimated from nuclease digestion assays.
Key Words:
AFM, DNA, chromatin, nucleosome, single molecule
