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Mitochondrial processing peptidase: multiple-site recognition of precursor proteins
1Department of Molecular Chemistry, Graduate School of Science, Kyushu University, Fukuoka, 812-8581, Japan. a.itoscc@mbox.nc.kyushu-u.ac.jp
Abstract:
During or shortly after import of the precursor proteins into mitochondria, the amino-terminal extension peptides are first proteolytically removed by mitochondrial processing peptidase (MPP). The peptidase is a metalloendopeptidase, classified as a member of pitrilysin family, and forms a heterodimer consisting of structurally related alpha- and beta-subunits which are homologous to core proteins, core 2 and core 1, respectively, of mitochondrial ubiquinol-cytochrome c oxidoreductase complex. The enzyme specifically recognizes a large variety of mitochondrial precursor proteins and is cleaved at a single and specific site. In this review, I will focus on recognition mechanisms of precursor proteins by MPP. Structural characteristics of the precursor responsible for the recognition by MPP, role of each subunit, and amino acid residues of MPP involved in the recognition are discussed.
Insights
Mitochondrial processing peptidase (MPP) removes amino-terminal peptides from precursor proteins. This review details how MPP recognizes specific protein sequences and cleavage sites, involving its subunits and amino acid residues.
Area of Science:
- Mitochondrial biology
- Protein processing
- Enzymology
Background:
- Mitochondrial precursor proteins require processing after import.
- Mitochondrial processing peptidase (MPP) is crucial for this initial step.
- MPP is a metalloendopeptidase belonging to the pitrilysin family.
Purpose of the Study:
- To review the recognition mechanisms of mitochondrial precursor proteins by MPP.
- To elucidate the structural features of precursors that mediate MPP recognition.
- To discuss the roles of MPP subunits and specific amino acid residues in substrate recognition.
Main Methods:
- Literature review focusing on structural and biochemical studies of MPP.
- Analysis of known MPP cleavage sites and precursor protein structures.
- Examination of studies detailing MPP subunit composition and function.
Main Results:
- MPP forms a heterodimer of alpha- and beta-subunits, homologous to mitochondrial ubiquinol-cytochrome c oxidoreductase core proteins.
- MPP exhibits broad substrate specificity, recognizing diverse mitochondrial precursor proteins.
- Cleavage occurs at a single, specific site within the precursor proteins.
Conclusions:
- The recognition of mitochondrial precursor proteins by MPP is a complex process involving specific structural features of the precursor.
- Both MPP subunits and critical amino acid residues within MPP play essential roles in mediating substrate recognition and cleavage.
- Understanding these mechanisms is vital for comprehending mitochondrial biogenesis and function.