The Molecular Chaperone Mechanism of the C-Terminal Domain of Large-Size Subunit Catalases.

Large-size subunit catalases (LSCs) have an additional C-terminal domain (CT) that is structurally similar to Hsp31 and DJ-1 proteins, which have molecular chaperone activity. The CT of LSCs derives from a bacterial Hsp31 protein. There are two CT dimers with inverted symmetry in LSCs, one dimer in each pole of the homotetrameric structure.

Large-Size Subunit Catalases Are Chimeric Proteins: A HO Selecting Domain with Catalase Activity Fused to a Hsp31-Derived Domain Conferring Protein Stability and Chaperone Activity.

Bacterial and fungal large-size subunit catalases (LSCs) are like small-size subunit catalases (SSCs) but have an additional C-terminal domain (CT). The catalytic domain is conserved at both primary sequence and structural levels and its amino acid composition is optimized to select HO over water. The CT is structurally conserved, has an amino acid composition similar to very stable proteins, confers high stability to LSCs, and has independent molecular chaperone activity.

Chaperone activity of large-size subunit catalases.

Large-size subunit catalases (LSCs) have a C-terminal domain that is structurally similar to DJ-1 and Hsp31 proteins, which have well documented molecular chaperone activity. Like chaperones, LSCs are abundant proteins that are induced under stress conditions and during cell differentiation in different microorganisms. Here we document that the C-terminal domain of LSCs assist other proteins to preserve their active conformation.