hide
Free keywords:
Adenosine Triphosphate/pharmacology
Endopeptidases/metabolism
HSP70 Heat-Shock Proteins/metabolism
Membrane Proteins/metabolism
Mitochondria/*metabolism
Models, Biological
Proteins/metabolism
Serine Endopeptidases
Abstract:
Various adenosine triphosphate (ATP)-dependent proteases were identified within mitochondria which mediate selective mitochondrial protein degradation and fulfill crucial functions in mitochondrial biogenesis. The matrix-localized PIM1 protease, a homologue of the Escherichia coli Lon protease, is required for respiration and maintenance of mitochondrial genome integrity. Degradation of non-native polypeptides by PIM1 protease depends on the chaperone activity of the mitochondrial Hsp70 system, posing intriguing questions about the relation between the proteolytic system and the folding machinery in mitochondria. The mitochondrial inner membrane harbors two ATP-dependent metallopeptidases, the m- and the i-AAA protease, which expose their catalytic sites to opposite membrane surfaces and cooperate in the degradation of inner membrane proteins. In addition to its proteolytic activity, the m-AAA protease has chaperone-like activity during the assembly of respiratory and ATP-synthase complexes. It constitutes a quality control system in the inner membrane for membrane-embedded protein complexes.
