Structure and Function of the Ankyrin Repeats in the SW14/SW16 TranscriptionComplex of Budding Yeast

摘要

Ankyrin repeats are motifs of thirty three amino acid residues, which are foundin over 100 proteins. Several of these are of particular interest because they suggest roles for the ankyrin repeat in tumor development. ANK repeats were first identified in a pair of yeast transcription factors (Swi4 and Swi6), and this research is focused upon understanding the role of the ANK repeats within these proteins. We have generated libraries of PCR-generated mutants of the Swi6 ANK domain and analyzed them with respect their transcriptional activity and sequence changes. We also used site-directed mutagenesis to systematically remove the core residues from each of the 4 ANK repeats, and found that the ANK core mutants as well as many of the random mutants are temperature sensitive for activity. This suggests that this region of the Swi6 protein is critical for the stability of the protein. We then isolated high copy suppressors of these mutants. Two gene products known to be involved in transcription and DNA interaction were identified (NHP6A and MSNl) as well as a novel protein (PIBi). The significance of these interactions is under investigation.