Role for the mitochondrial inner membrane in the maturation of the precursor to ornithine carbamyl transferase.
The precursor to ornithine carbamyl transferase (pOCT) is cleaved at two N-terminal sites when imported into intact mitochondria but only at the N-proximal site when incubated with a membrane-free mitochondrial lysate or matrix fraction. Disruption of the mitochondrial membrane system by sonication, freeze-thaw, or lysis with non-ionic detergents blocks the processing of pOCT to its mature form. Mitoplasts prepared from protease-inactivated, import-incompetent mitochondria recover full processing activity; disruption of the inner membrane impairs the maturation process i.e. causes the loss of the mitoplasts' ability to transform pOCT into OCT. The data reveal a dependency of a maturation event on a "specific" interaction between a precursor protein and the mitochondrial inner membrane probably to position and/or to expose the correct N-distal cleavage site of the presequence.
Côté
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Université du Québec à Montréal, Department of Chemistry, Canada.
Poirier
J
J
Boulet
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D
D000818:Animals; D004792:Enzyme Precursors / Q000378:metabolism*; D007425:Intracellular Membranes / Q000201:enzymology / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000201:enzymology / Q000378:metabolism*; D009954:Ornithine Carbamoyltransferase / Q000378:metabolism*; D051381:Rats
D004792:Enzyme Precursors; D009954:Ornithine Carbamoyltransferase