A novel meiosis-specific protein of fission yeast, Meu13p, promotes homologous pairing independently of homologous recombination

Meiotic homologous pairing is crucial to proper homologous recombination, w hich secures subsequent reductional chromosome segregation. We have identif ied a novel meiosis-specific protein of fission yeast Schizosaccharomyces p ombe, Meu13p, to be a molecule that is required for proper homologous pairi ng and recombination. Rec12p (homologue of Saccharomyces cerevisiae Spo11p) , which is essential for the initiation of meiotic recombination, is also s hown for the first time to participate in the pairing process of S. pombe. Meu13p, however, contributes to pairing through a recombination-independent mechanism, as disruption of the meu13(+) gene reduces pairing whether the rec12(+) gene is deleted or not. We also demonstrate a dynamic nature of ho mologous pairing in living meiotic cells, which is markedly affected by meu 13 deletion. Meu13p is not required for telomere clustering and the nuclear movement process, which are well known requirements for efficient pairing in S. pombe. Based on these results, together with the localization of Meu1 3p on meiotic chromatin, we propose that Meu13p directly promotes proper ho mologous pairing and recombination.