Chromatin folding and unfolding
He then returned to the LMB in 1970 as a staff scientist - a position he held until his retirement in 2008. At the LMB his work focussed on the organisation and three-dimensional structure of bacterial and eukaryotic chromatin with occasional forays into the roles of chromatin-associated proteins in Drosophila development.
We use Drosophila genetics and biochemistry to study the mechanisms of chromatin folding and unfolding. We have recently proposed a folding pathway for chromatin which postulates that the primary role of linker histones is to increase the twist of linker DNA thus converting two connected nucleosome stacks from a twisted to a parallel configuration.
The resulting compensating writhe then facilitates the concerted packing of the parallel stacks into a 2-start helical coil. This model predicts that proteins which twist or untwist the linker DNA will respectively fold and unfold the fibre. We have shown that in Drosophila chromatin folding, as assayed by the formation of pericientric heterochromatin, requires three remodelling assemblies, dISWI, dATRX and dMi-2 as well as an active sumoylation pathway.
Conversely two other remodellers, brahma and kismet, as well as the abundant HMGB proteins (which untwist linker DNA) are without effect.
- Ragab, A., Thompson, E. and Travers, A. (2006)
HmgD and HmgZ interact genetically with the Brahma chromatin remodeling complex in Drosophila.
Genetics 172: 1069-1078
- Wu, C. and Travers, A. (2005)
Relative affinities of DNA sequences for the histone octamer depend strongly upon both the temperature and octamer concentration.
Biochemistry 44: 14329-14334
- Dallman, J., Allopenna, J., Bassett, A., Travers, A. and Mandel, G. (2004)
A conserved role, but different partners for CoREST in fly and mammalian nervous system formation.
J Neurosci 24: 7186-7193