Probing the structural requirements for Mmi1's essential function in vegetative cells. (A) The amino acid sequence of S. pombe Mmi1 (Spo) is aligned to that of the homologous protein from S. japonicum (Sja). Positions of side chain identity/similarity are denoted by dots above the sequence. A conserved motif in the amino-terminal domain (aa 95–122) that suffices for Mmi1 interaction with Erh1 is underlined. The boundaries of the series of amino-terminal deletion alleles are indicated by rightward-pointing bent arrows. Amino acids in the carboxy-terminal YTH domain that were mutated to alanine are indicated by triangles above the sequence. (B) Viable mmi1–ΔN and mmi1-Ala strains were spot-tested for growth on YES agar at the indicated temperatures. Lethal mmi1–ΔN and mmi1-Ala alleles are indicated at bottom.
