Csm4, in Collaboration with Ndj1, Mediates Telomere-Led Chromosome Dynamics and Recombination during Yeast Meiosis

Abstract

Chromosome movements are a general feature of mid-prophase of meiosis. In budding yeast, meiotic chromosomes exhibit dynamic movements, led by nuclear envelope (NE)-associated telomeres, throughout the zygotene and pachytene stages. Zygotene motion underlies the global tendency for colocalization of NE-associated chromosome ends in a “bouquet.” In this study, we identify Csm4 as a new molecular participant in these processes and show that, unlike the two previously identified components, Ndj1 and Mps3, Csm4 is not required for meiosis-specific telomere/NE association. Instead, it acts to couple telomere/NE ensembles to a force generation mechanism. Mutants lacking Csm4 and/or Ndj1 display the following closely related phenotypes: (i) elevated crossover (CO) frequencies and decreased CO interference without abrogation of normal pathways; (ii) delayed progression of recombination, and recombination-coupled chromosome morphogenesis, with resulting delays in the MI division; and (iii) nondisjunction of homologs at the MI division for some reason other than absence of (the obligatory) CO(s). The recombination effects are discussed in the context of a model where the underlying defect is chromosome movement, the absence of which results in persistence of inappropriate chromosome relationships that, in turn, results in the observed mutant phenotypes.

The Nucleoporin Nup2 Contains a Meiotic-Autonomous Region that Promotes the Dynamic Chromosome Events of Meiosis

“…In both cases, the cause of spore death was skewed to NDD. This is consistent with NDD/RSD outcomes of TetFit analysis of previously published data sets for these genotypes (Wanat et al 2008), where the calculated NDD/RSD ratios for WT and ndj1D were 1.8%/1.8% and 20.8%/5.8%, respectively ( Figure S3).…”

“…At least 200 cells were analyzed for each time point. Lifespan analysis was carried out as previously described (Padmore et al 1991;Wanat et al 2008).…”

“…Ndj1 was purified according to the method of Puig et al (2001), with modifications: 4 liters of meiotic time course culture were harvested after 4 hr when bouquet formation peaks (Wanat et al 2008). The cell pellet was resuspended in lysis buffer [50 mM HEPES pH 7.5, 150 mM NaCl, 20% glycerol, 0.1% NP-40, 1 mM DTT, 1 mM PMSF, 10 mM sodium pyrophosphate, 50 mM NaF, 60 mM b-glycerophosphate, 13 Halt Protease Inhibitor Cocktail (ThermoFisher Scientific; Conrad et al 2008)].…”

“…The lifespan of the zygotene stage can be derived from the area under the curve of the primary data (Hunter and Kleckner 2001;Wanat et al 2008). An increase in lifespan compared to WT indicates a specific delay in passing through the corresponding stage (Hunter and Kleckner 2001).…”

“…This bridge directs telomere-led chromosome motion that is directed by cytoplasmic motor proteins (Conrad et al 2008;Kosaka et al 2008;Koszul et al 2008;Wanat et al 2008;Sonntag Brown et al 2011;Lee et al 2012). In budding yeast, Ndj1 accumulates at telomeres, and is required for bouquet formation via its interaction with Mps3 ( Figure 1A; Chua and Roeder 1997;Conrad et al 1997Conrad et al , 2007Scherthan 2007).…”