MER1, A YEAST GENE REQUIRED FOR CHROMOSOME-PAIRING AND GENETIC-RECOMBINATION, IS INDUCED IN MEIOSIS

The yeast MER1 gene is required for the production of viable meiotic products and for meiotic recombination. Cytological analysis of chromosome spreads from a mer1 mutant indicates that the MER1 gene product is also required for normal chromosome pairing, mer1 strains make axial elements, precursors to the synaptonemal complex; however, the chromosomes in most nuclei do not become fully synapsed. The DNA sequence of the MER1 coding region was determined; the MER1 open reading frame encodes a 270-amino-acid protein with a molecular mass of 31.1 kilodaltons. The MER1 protein shows limited sequence similarity to calmodulin. Expression of the MER1 gene was examined by RNA blot hybridization analysis and through the construction and analysis of mer1::lacZ fusion genes. Expression of the MER1 gene is meiotically induced and required the IME1 gene product. Thus, expression of the MER1 gene early in meiosis is required for proper chromosome pairing and meiotic recombination.