Nam8 domain organization and requirements for sporulation. (A) The amino acid sequence of S. cerevisiae (Sce) Nam8 from residues 28–523 is aligned to the sequence of A. gossypii (Ago) Nam8. Positions of amino acid side chain identity/similarity are denoted by • above the sequence. RNP2 and RNP1 motifs of the RRMs are indicated by brackets under the sequence. Positions within the motifs of the RRM2 and RRM3 domains that comprise the putative RNA-binding surface and were subjected to alanine cluster mutagenesis are denoted by ▾ above the sequence. Forward and reverse arrows indicate the boundaries of the N- and C-terminal truncations of Nam8, respectively. (B, top) Schematic representation of Nam8 domain organization; the RRMs are depicted as cylinders. (Bottom) nam8Δ diploids with the indicated NAM8 alleles integrated at the chromosomal LEU2 locus were examined by light microscopy at 6, 8, 10, 12, 14, and 24 h after transfer to sporulation medium. The percentages of the cell population comprising four-spore asci were gauged. The bar graph shows the extents of sporulation at 24 h. Each datum is the average of three independent experiments ±SEM.
