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SUMMARY:Structure and Activity of the Histone H3/H4 Chaperone Asf1 - Prof.
  Mair Churchill\, Univ. of Colorado\, USA
DTSTART:20110802T151500Z
DTEND:20110802T160000Z
UID:TALK32215@talks.cam.ac.uk
CONTACT:M. Madan Babu
DESCRIPTION:Together with non-histone proteins nucleosomes assemble the eu
 karyotic genome into higher order structures known as chromatin. Chromatin
  structure is dynamic\, as it is continually assembled and disassembled fo
 r factors that carry out the processes of transcription\, replication\, DN
 A repair\, and recombination to gain access to the DNA. The deposition of 
 the histones H3/H4 onto DNA to give the tetrasome intermediate and the dis
 placement of H3/H4 from DNA are thought to be first and last steps in nucl
 eosome assembly and disassembly\, respectively.\n\nAnti-silencing function
  1 (Asf1) is a chaperone of the H3/H4 dimer that functions in both of thes
 e processes.  We have examined the molecular basis of the activity of Asf1
  in nucleosome assembly and disassembly using a variety of methods\, inclu
 ding X-ray crystallography\, biophysical and biochemical methods.  The str
 ucture of the globular domain of Asf1 bound to histones H3/H4 shows how As
 f1 binds to the H3/H4 heterodimer\, enveloping the C-terminus of histone H
 3\, and physically blocks the formation of the H3/H4 heterotetramer. \n\nB
 iophysical studies have revealed the ability of Asf1 to directly deposit H
 3/H4 dimers onto the DNA\, but suggest that additional factors are require
 d for their removal from DNA.  Quantitative binding studies have character
 ized specific Asf1-H3/H4 interactions and provided insight into the hand-o
 ff of histones to other histone chaperones\, providing insight into the mo
 lecular mechanisms of DNA accessibility that are essential and fundamental
  to all DNA-dependent cellular functions.\n
LOCATION:Max Perutz Lecture Theatre\, MRC Laboratory of Molecular Biology\
 , Cambridge\, UK
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