Mitochondrial localization and oligomeric structure of HClpP, the human homologue of E. coli ClpP.
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de Sagarra MR, Mayo I, Marco S, Rodriguez-Vilarino S, Oliva J, Carrascosa JL, Casta n JG
Mitochondrial localization and oligomeric structure of HClpP, the human homologue of E. coli ClpP.
J Mol Biol. 1999 Oct 1;292(4):819-25.
- PubMed ID
- 10525407 [ View in PubMed]
- Abstract
A bacterially expressed recombinant HClpP protein, the human homologue of Escherichia coli ClpP protease, was used to obtain specific polyclonal antibodies. Those antibodies identify a 26 kDa polypeptide in mitochondrial subcellular fractions of rat and human liver. Immunofluorescence and electron microscopic studies demonstrate that the mammalian homologue of ClpP is located in the mitochondrial matrix with a tendency to be found in association with the inner mitochondrial membrane. An HClpP recombinant protein with a truncated NH2terminus (missing the first 58 amino acid residues) shows a molecular mass of 26 kDa under denaturing conditions. This N-truncated HClpP recombinant protein shows a native molecular mass of 340 kDa that is identical with the native molecular mass of the partially purified protein from rat liver mitochondria. Electron microscopy shows that the N-truncated recombinant HClpP has a ring shape with seven identical morphological units in the periphery, exhibiting a 7-fold symmetry. The native molecular mass and the electron microscopic studies suggest that mitochondrial ClpP is composed of two heptameric rings with 7-fold symmetry, similar to E. coli ClpP.