Abstract
The spindle checkpoint ensures the accurate segregation of chromosomes by monitoring the status of kinetochore attachment to microtubules. Simultaneous mutations in one of several kinetochore and cohesion genes and a spindle checkpoint gene cause a synthetic-lethal or synthetic-sick phenotype. A synthetic genetic array (SGA) analysis using a mad2Δ query mutant strain of yeast identified YBP2, a gene whose product shares sequence similarity with the product of YBP1, which is required for H2O2-induced oxidation of the transcription factor Yap1. ybp2Δ was sensitive to benomyl and accumulated at the mitotic stage of the cell cycle. Ybp2 physically associates with proteins of the COMA complex (Ctf19, Okp1, Mcm21, and Ame1) and 3 components of the Ndc80 complex (Ndc80, Nuf2, and Spc25 but not Spc24) in the central kinetochore and with Cse4 (the centromeric histone and CENP-A homolog). Chromatin-immunoprecipitation analyses revealed that Ybp2 associates specifically with CEN DNA. Furthermore, ybp2Δ showed synthetic-sick interactions with mutants of the genes that encode the COMA complex components. Ybp2 seems to be part of a macromolecular kinetochore complex and appears to contribute to the proper associations among the central kinetochore subcomplexes and the kinetochore-specific nucleosome.
Highlights
The centromere interacts with the spindle fibers to ensure the correct segregation of chromosomes during mitotic and meiotic cell divisions
To identify genes that regulate mitosis in yeast, an synthetic genetic array (SGA) screen of the mad2D strain as a query mutation was performed against a complete set of deletion-mutant yeast strains [24]
Ybp2Dmad2D exhibited an enhanced chromosomemissegregation phenotype as compared with either single mutant (Figure 2B). These results suggest that the mitotic defect caused by deletion of YBP2 is monitored by the spindle checkpoint, and the ybp2D cells are protected from chromosome missegregation
Summary
The centromere interacts with the spindle fibers to ensure the correct segregation of chromosomes during mitotic and meiotic cell divisions. We characterized the mitotic function of Ybp2 that was identified by an SGA screen by using the mad2-deletion (mad2D) strain. Synthetic Genetic Array (SGA) Screen of mad2D Mutants Identified YBP2 as a Mitotic Factor
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
