2hue: Difference between revisions

[[Image:2hue.gif|left|200px]]<br /><applet load="2hue" size="350" color="white" frame="true" align="right" spinBox="true"  

Anti-silencing function 1 (Asf1) is a highly conserved chaperone of histones H3/H4 that assembles or disassembles chromatin during transcription, replication, and repair. The structure of the globular domain of Asf1 bound to H3/H4 determined by X-ray crystallography to a resolution of 1.7 Angstroms shows how Asf1 binds the H3/H4 heterodimer, enveloping the C terminus of histone H3 and physically blocking formation of the H3/H4 heterotetramer. Unexpectedly, the C terminus of histone H4 that forms a mini-beta sheet with histone H2A in the nucleosome undergoes a major conformational change upon binding to Asf1 and adds a beta strand to the Asf1 beta sheet sandwich. Interactions with both H3 and H4 were required for Asf1 histone chaperone function in vivo and in vitro. The Asf1-H3/H4 structure suggests a "strand-capture" mechanism whereby the H4 tail acts as a lever to facilitate chromatin disassembly/assembly that may be used ubiquitously by histone chaperones.

2HUE is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Saccharomyces_cerevisiae Saccharomyces cerevisiae] and [http://en.wikipedia.org/wiki/Xenopus_laevis Xenopus laevis] with <scene name='pdbligand=SO4:'>SO4</scene>, <scene name='pdbligand=ZN:'>ZN</scene> and <scene name='pdbligand=GOL:'>GOL</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2HUE OCA].  

[[Category: Churchill, M E.A.]]

[[Category: English, C M]]

[[Category: Tyler, J K.]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:45:48 2008''