FIG. 7.

The C-terminal region of Ssy5 shows similarity to S1-family serine proteases. (Top) Schematic representation of the domain structure of the Ssy5 protein. The C-terminal serine-protease-like domain (residues 459 to 687) defined by the Superfamily program is boxed. The approximate relative positions of the histidine (H), aspartate (D), and serine (S) residues corresponding to the probable catalytic endoprotease site of Ssy5 are indicated. The black box just upstream from the protease domain represents the position of the putative cleavage site of Ssy5 (see Fig. 8). The horizontal line with arrows delimits the Ssy5 region most highly conserved between Ssy5 proteins of various fungal species. (Bottom) Sequence logos taken from HMM 0011293 around residues of the catalytic triad (see text). The greater the height of the amino acid (single-letter code), the higher its conservation in the HMM alignment. Ssy5 sequences around the three amino acids (positions 465, 545, and 640) are also shown. The seed sequence used to initiate building of HMM 0011293 was the catalytic domain of the HtrA protease of E. coli (39). The sequence of the catalytic triad of HtrA is also shown.