Gcn5p Plays an Important Role in Centromere Kinetochore Function in Budding Yeast

Abstract

We report that the histone acetyltransferase Gcn5p is involved in cell cycle progression, whereas its absence induces several mitotic defects, including inefficient nuclear division, chromosome loss, delayed G₂ progression, and spindle elongation. The fidelity of chromosome segregation is finely regulated by the close interplay between the centromere and the kinetochore, a protein complex hierarchically assembled in the centromeric DNA region, while disruption of GCN5 in mutants of inner components results in sick phenotype. These synthetic interactions involving the ADA complex lay the genetic basis for the critical role of Gcn5p in kinetochore assembly and function. We found that Gcn5p is, in fact, physically linked to the centromere, where it affects the structure of the variant centromeric nucleosome. Our findings offer a key insight into a Gcn5p-dependent epigenetic regulation at centromere/kinetochore in mitosis.

ACKNOWLEDGMENTS

This work was funded by RTL-CNR 2005 to P.F. and by Fondazione Pasteur Istituto Cenci-Bolognetti to P.B. S.V. was supported by Ministero dell'Interno, Dip. P.S.

We thank S. Piatti for helpful advice, for providing the strains, and for help with the experiment shown in Fig. 4. We thank L. Guarente, M. H. Kuo, T. Stearn, S. Berger, B. Stilmann, and P. DeWulf for providing mutant strains and plasmids. We are particularly indebted to E. Marchetti for his skillful technical assistance in confocal microscopy and video time-lapse experiments.