Rhodanese (E.C. 188.8.131.52) is a thiosulfate:cyanide sulfurtransferase found in the matrix of mitochondria. Its NH2-terminal sequence is necessary for import into the mitochondria, but is not proteolytically cleaved after import. Data is presented supporting the hypothesis that the NH2-terminal sequence of rhodanese contributes to folding and maintaining a stable, active conformation of the protein. A series of truncation mutants that sequentially deleted amino acid residues through residue K23 from the NH2-terminus of the protein was constructed and expressed in Eseherichia coll. Susceptibility to degradation by host cells indicated protein instability when 10-23 residues were deleted. Purification and characterization of stable mutants with up to 9 residues deleted indicated similar catalytic activity properties but different stability properties and different refolding properties when compared with wildtype. Longer truncations corresponded to decreased stability as measured by urea perturbation. The extent of unassisted refolding was increased and the rate of GroEL/ESassisted refolding was decreased with deletion of NH2-terminal residues. Truncation of the NH2-terminal sequence of rhodanese can trigger conformational instability leading to inactivity due to disruption of the micro-environment of the aclive site.
|Original language||English (US)|
|State||Published - Dec 1 1997|
ASJC Scopus subject areas
- Molecular Biology