Spo13

Spo13 is a meiosis-specific protein in the budding yeast Saccharomyces cerevisiae. It plays a role in regulating chromosome behavior during meiosis I, the division in which homologous chromosomes separate while sister chromatids largely stay joined. Spo13 helps establish the meiosis I–specific pattern of cohesion and separation, contributing to the reductional division that characterizes meiosis I. The precise molecular mechanism is not fully resolved, but Spo13 is thought to influence the activity or localization of cohesin complexes and separase indirectly, helping to prevent premature sister-chromatid separation during meiosis I.

Expression of Spo13 is restricted to meiosis, and the protein localizes to the nucleus during meiotic prophase and metaphase I. It is not essential for mitotic growth, indicating a specialized function for meiotic chromosome segregation. Deletion of SPO13 (spo13Δ) leads to defects in meiotic chromosome segregation, including missegregation of homologs and inappropriate loss of centromeric cohesion, which can result in reduced spore viability.

Spo13 is part of a broader meiotic regulatory network that includes cohesin protection mechanisms and factors that regulate sister-chromatid cohesion and separase activity. Studied to understand the coordination of cohesion and disjunction in meiosis, Spo13 contributes to the overall understanding of meiotic chromosome dynamics in budding yeast.