Histone Octamer Helical Tubes Suggest that an Internucleosomal Four-Helix Bundle Stabilizes the Chromatin Fiber

A new fluorescence resonance energy transfer approach demonstrates that the histone variant H2AZ stabilizes the histone octamer within the nucleosome.

Nucleosomes are highly dynamic macromolecular complexes that are assembled and disassembled in a modular fashion. One important way in which this dynamic process can be modulated is by the replacement of major histones with their variants, thereby affecting nucleosome structure and function. Here we use fluorescence resonance energy transfer between fluorophores attached to various defined loca...

A new FRET approach demonstrates that the histone variant H2AZ stabilizes the histone octamer within the nucleosome

Histone Octamer Transfer by a Chromatin-Remodeling Complex

RSC, an abundant, essential chromatin-remodeling complex related to SWI/SNF complex, catalyzes the transfer of a histone octamer from a nucleosome core particle to naked DNA. The newly formed octamer-DNA complex is identical with a nucleosome in all respects. The reaction requires ATP and involves an activated RSC-nucleosome intermediate. The mechanism may entail formation of a duplex displacem...

H2A.Z stabilizes chromatin in a way that is dependent on core histone acetylation.

The functional and structural chromatin roles of H2A.Z are still controversial. This work represents a further attempt to resolve the current functional and structural dichotomy by characterizing chromatin structures containing native H2A.Z. We have analyzed the role of this variant in mediating the stability of the histone octamer in solution using gel-filtration chromatography at different pH...

The design of a four-helix bundle protein.

The design of proteins with predetermined structural properties is a necessary first step in the de novo design of novel enzymes and receptors. A major problem associated with the design of proteins is the high flexibility inherent in polypeptide chains. It has been estimated that a protein of 100 residues can adopt up to 101~176 different conformations, a number that is as large as the number ...