Abstract
Histone tail phosphorylation has diverse effects on a myriad of cellular processes, including cell division, and is highly conserved throughout eukaryotes. Histone H3 phosphorylation at threonine 3 (H3T3) during mitosis occurs at the inner centromeres and is required for proper biorientation of chromosomes on the mitotic spindle. While H3T3 is also phosphorylated during meiosis, a possible role for this modification has not been tested. Here, we asked if H3T3 phosphorylation is important for meiotic division by quantifying sporulation efficiency and spore viability in Saccharomyces cerevisiae mutants with a T3A amino acid substitution. The T3A substitution resulted in reduced sporulation efficiency and reduced spore viability. Analysis of two other H3 tail mutants, K4A and S10A, revealed different effects on sporulation efficiency and spore viability compared to the T3A mutant, suggesting that these phenotypes may be due to failures in distinct functions. To determine if the spindle checkpoint promotes spore viability of the T3A mutant, the MAD2 gene was deleted. This resulted in a severe reduction in spore viability following meiosis. Altogether, the data reveal an important function for histone H3 threonine 3 that requires monitoring by the spindle checkpoint to ensure successful completion of meiosis.