Editor: David Goldfarb
The budding yeast protein Sum1 functions independently of its binding partners Hst1 and Sir2 histone deacetylases to regulate microtubule assembly
Article first published online: 7 JUN 2010
© 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved
FEMS Yeast Research
Volume 10, Issue 6, pages 660–673, September 2010
How to Cite
Sarkar, S., Haldar, S., Hajra, S. and Sinha, P. (2010), The budding yeast protein Sum1 functions independently of its binding partners Hst1 and Sir2 histone deacetylases to regulate microtubule assembly. FEMS Yeast Research, 10: 660–673. doi: 10.1111/j.1567-1364.2010.00655.x
- Issue published online: 12 AUG 2010
- Article first published online: 7 JUN 2010
- Received 18 February 2010; revised 12 May 2010; accepted 27 May 2010.Final version published online 30 June 2010.
- dosage suppression;
- microtubule assembly;
The budding yeast protein Sum1 is a transcription factor that associates with the histone deacetylase Hst1p or, in its absence, with Sir2p to form repressed chromatin. In this study, SUM1 has been identified as an allele-specific dosage suppressor of mutations in the major α-tubulin-coding gene TUB1. When cloned in a 2μ vector, SUM1 suppressed the cold-sensitive and benomyl-hypersensitive phenotypes associated with the tub1-1 mutation. The suppression was Hst1p- and Sir2p-independent, suggesting that it was not mediated by deacetylation events associated with Sum1p when it functions along with its known partner histone deacetylases. This protein was confined to the nucleus, but did not colocalize with the microtubules nor did it bind to α- or β-tubulin. Cells deleted of SUM1 showed hypersensitivity to benomyl and cold-sensitive growth, phenotypes exhibited by mutants defective in microtubule function and cytoskeletal defects. These observations suggest that Sum1p is a novel regulator of microtubule function. We propose that as a dosage suppressor, Sum1p promotes the formation of microtubules by increasing the availability of the αβ-heterodimer containing the mutant α-tubulin subunit.