In eukaryotes, the manipulation of chromatin structure represents a means of regulating access to genetic information. One way in which this can be achieved is via the action of ATP-dependent chromatin remodelling complexes related to the S.cerevisiae Snf2 proteins. The Fun30 protein (Function unknown now 30) shares sequence homology with the Snf2 family of chromatin remodelling proteins. Here the activities and roles of Fun30 have been investigated further. In this study, Fun30 was found to exist predominantly as a homodimer with an apparent molecular weight of 250 KDa. Fun30 binds to DNA, mononucleosomes and nucleosomal arrays. Moreover, Fun30 was shown to cause ATP-dependent alterations to nucleosome structure. This can involve increasing the accessibility of DNA, octamer displacement by sliding in cis or transfer to separate DNA molecules.However, Fun30 was shown to be proficient in catalysing the exchange of histone dimers. Deletion of fun30 was observed to increases resistance to UV, IR and 6-azauracil raising the possibility that this protein has functions in DNA repair. Deletion of fun30 was also found to result in temperature sensitivity. At the non permissive temperature cells were found to accumulate in the S-phase of the cell cycle. Under these conditions Rad53 was found to be phosphorylated which is consistent with the activation of the S-phase checkpoint. In order to investigate the role of Fun30 in DNA replication samples were prepared to map the genome-wide locations of Fun30 at different stages in the cell cycle. Preliminary analysis of this data suggests that there is a transient enrichment of Fun30 protein within the vicinity of replication origins during S-phase.
|Date of Award
|Tom Owen-Hughes (Supervisor)