ISSN:
1617-4623
Keywords:
PP2A Cdc55 Phosphatase Yeast Checkpoint
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract. Protein phosphatase 2A is ubiquitous among eukaryotes and exists as a family of holoenzymes in which the catalytic subunit, PP2Ac, binds a variety of regulatory subunits. Using the yeast Saccharomyces cerevisiae, we have investigated the role of the phylogenetically invariant C-terminal leucine residue of PP2Ac, which, in mammalian cells, undergoes reversible methylation and modulates binding of the PR55/B subunit. In S. cerevisiae, the C-terminal Leu-377 residue of Pph22p (equivalent to human PP2Ac Leu-309) was dispensable for cell growth under optimum conditions and its removal, or substitution by alanine, did not inhibit PP2A activity in vitro. However, Leu-377 is required for binding of the yeast PR55/B subunit, Cdc55p, by Pph22p, though apparently not for the binding of Rts1p, the yeast PR61/B′ subunit. Furthermore, mutation of this leucine enhanced the sensitivity of cells to microtubule destabilization, a defect characteristic of cdc55 Δ mutant cells, which are impaired for spindle checkpoint function. These results demonstrate that the regulation of PP2A, mediated by PR55/B binding to the highly conserved PP2Ac C-terminus, is critical for cell viability under conditions of microtubule damage and support a role for PP2A in exit from mitosis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004380000302
