Job Description

SULSA Prize PhD Studentship
- Allshire Lab, Wellcome Trust Centre for Cell Biology, Edinburgh, UK

Description: Assembly of fission yeast CENP-A and H3 chromatin in vivo and in vitro.

The fundamental component distinguishing centromeres from chromosome arms is the histone H3-variant CENP-A.  CENP-A is only incorporated at active centromeres, how this is accomplished is largely unknown.

We identified two proteins in fission yeast (Sim1 and Sim3) that are required maintain CENP-A chromatin.  In sim1 and sim3 mutants histone H3 remains in place at centromeres.  Sim3 is related to NASP/N1-N2 (H3/H4 chaperones) and probably escorts CENP-A to centromeres, handing it over to factors that replace H3 with CENP-A.  Sim1 is the ortholog of S. cerevisiae Scm3 which binds CENP-A and acts to remove H2A-H2B dimers from centromeric nucleosomes leaving a putative hexamer of Scm3-CENP-A-H4 forming a highly unusual ‘nucleosome’.  Scm3 also contacts the centromeric CDEIII-DNA binding factor Ndc10.  Human and fission yeast lack such a specific DNA binding factor and CENP-A chromatin probably retains H2A and H2B.  We suspect that fission yeast Sim1^Scm3 may act to disassemble H3 containing nucleosomes that remain in centromeric chromatin and reassemble CENP-A in its place.  In general, the first step of nucleosome disassembly is the removal of the H2A-H2B dimer facilitating opening of the H3-H4 tetramer (eg FACT reassembles H2A-H2B before/after advancing RNAPII).  We propose that in fission Sim1^Scm3 act transiently to open H3 nucleosomes by destabilising H2A-H2B dimers and subsequently to reassemble H2A-H2B dimers into nucleosomes in which H3 has been replaced by CENP-A.  Testing this requires recombinant CENP-A and H3 nucleosomes formed from fission yeast histones. Production of recombinant histones,  in vitro chromatin assembly and in vitro remodelling assays will be performed in collaboration with Tom Owen-Hughes (Dundee). Assays will be set up to assess relative association of histones with Sim3^NASP and Sim1^Scm3 and if they facilitate exchange. We aim to recapitulate the steps of CENP-A chromatin assembly in vitro utilising proteins and complexes identified as being important in vivo.

Qualifications: Candidates will ideally have a B.Sc. or M.Sc. in a relevant discipline, with some experience in Biochemistry and/or Molecular biology. An obvious knowledge of, and interest, in chromatin assembly would also be beneficial.

Salary Details: These positions will be by SULSA:
The Scottish Universities Life Sciences Alliance
SULSA is an alliance of six universities aimed at embedding the Life Sciences in Scotland as a world leading force by bringing together resources and coherent planning of research strategy. The formation of SULSA has been boosted by a £76m investment programme supported by the Scottish Funding Council (SFC) and the constituent universities. SULSA is offering PhD studentships in its three research themes: Cell Biology, Systems Biology and Translational Biology. Every project will be based in the laboratory of the primary supervisor and will benefit from collaboration and cooperation with a second supervisor in another SULSA institution. All students will be integrated into SULSA’s research network across Scotland. For more information see the SULSA website: http://www.sulsa.ac.uk

Application Details: Interested candidates should send a detailed CV (including names and contact details of two referees) with covering letter via e-mail (in word or PDF format only) to Prof. Robin Allshire.

Closing Date: 2008-01-11