FIG. 1.

The putative Candida albicans HSP104 gene encodes an 899-residue protein that contains all of the key sequence features of the S. cerevisiae molecular chaperone Hsp104. (A) Domain organization of S. cerevisiae Hsp104 (ScHsp104) and C. albicans Hsp104 (CaHsp104) proteins and % amino acid identity at the domain level between the two proteins. The domains were identified by sequence comparison with the Escherichia coli ClpB protein sequence and structure (25). The residues that define the approximate positions of these domains are indicated for ScHsp104 (above) and CaHsp104 (below). (B) Alignment of amino acid sequences of putative Hsp104 orthologues from fungi and Arabidopsis thaliana. Three regions implicated in ATP binding or hydrolysis are shown, with invariant residues boxed. The sequences were obtained from GenBank, and the species are as follows: Sc, Saccharomyces cerevisiae; Sb, Saccharomyces bayanus; Spx, Saccharomyces paradoxus; Sm, Saccharomyces mikatae; Sct, Saccharomyces castellii; Sk, Saccharomyces kudriavzevii; Ca, Candida albicans; Spm, Schizosaccharomyces pombe; Nc, Neurospora crassa; and At, Arabidopsis thaliana. (C) The C-terminal 20 residues of members of the Hsp104 family, including CaHsp104, contain large proportions of the acidic residues D and E (in bold) and two highly conserved residues (LD; boxed) at the extreme C terminus.