Proteases 4 Flashcards
What are the three types of mitochondrial proteases?
Processing proteases which remove the mitochondrial targeting sequence from proteins, ATP dependent proteases which largely degrades old unwanted proteins
Oligoproteases which degrade the small pepeitdes formed from ATP dependant proteases
How are mitochondrial proteases degraded?
The mitochondrial proteolytic system
Where do mitochondrial proteins come from?
Encoded by either nuclear or mitochondrial DNA and synthesized by cytosolic or mitochondrial ribosomes respectively
What are the processing peptidases?
Mitochondrial Processing Peptidase, Mitochondrial intermediate peptidase
Inner membrane peptidase
ATP23
Rhomboid protease
What is mitochondrial processing peptidase?
A metalloprotease in the mitochondrial matrix which has a catalytic alpha unit and regulatory beta unit. Cleaves the mitochondrial targeting sequence in the matrix
What is mitochondrial intermediate peptidase?
A metalloprotease in the mitochondrial matrix which acts to release the N terminal octopeptide as a second stage of processing for some proteins that enter the mitochondria
What is inner membrane peptidase?
a serine protease in the inner membrane (active site exposed to IMS) with non-catalytic Som1 and catalytic subunits Imp1 and Imp2, which functions to process both nuclear- and mitochondrially-encoded proteins targeted to the IMS.
What is ATP23
A metalloprotease found in the intermembrane space which is needed for the assembly of ATP synthase by first removing the 10 N-terminal residues of subunit 6 of ATP synthase, then in assembly of the membrane-embedded Fo particle.
What is rhomboid protease?
Serine proteases in the inner membrane, the rhomboid protease cleaves membrane anchored proteins within transmembrane sequencing
What are the ATP dependant proteases of mitochondria?
Multimeric proteins with proteolytic regions and ATPase domains
The ATPase domain is used to gain energy which can be used to unfold proteins
They are AAA+ proteins meaning that they have ATPase domains that can assemble into oligomeric structures
i-AAA and m-AAA, Lon-protease, ClpX are present in the mitochondria
What is i-AAA?
A metalloprotease active in the intermembrane space and degrades misfolded mitochondrial proteins
What are m-AAA?
A metalloprotease active on the matrix side of the membrane which has multiple functions
What functions are shared between m-AAA and i-AAA?
Protein turnover providing quality control
Processing of mitochondrial targeting sequencing
Membrane dislocation
Protein import
What is the Lon-protease?
A serine protease of the mitochondrial matrix which performs quality control and is important during heat and oxidative stress situations
Action requires:
Recognition and binding of the substrate
ATP hydrolysis then enables further unfolding of the damaged protein
More ATP hydrolysis allows the protein to be translocated into the proteolytic domain
Proteolysis
What is the ClpXP protease?
Serine protease of the mitochondrial matrix
Performs quality control of proteins destroying those with an identifiable tag
