The β Subunit of the Mitochondrial Processing Peptidase From Rat Liver: Cloning and Sequencing of a cDNA and Comparison With a Proposed Family of Metallopeptidases

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 90; no. 11; pp. 5355 - 5358
• Main Authors: Paces, Vaclav, Rosenberg, Leon E., Fenton, Wayne A., Kalousek, Frantisek
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01-06-1993; National Acad Sciences
• Subjects: Amino Acid Sequence; Amino acids; Analytical, structural and metabolic biochemistry; Animals; Base Sequence; Biochemistry; Biological and medical sciences; Cattle; Cloning, Molecular; Complementary DNA; DNA - genetics; DNA - isolation & purification; Enzymes; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; Hydrolases; Liver; Liver - enzymology; Macromolecular Substances; Metalloendopeptidases - genetics; Mitochondria, Liver - enzymology; Mitochondrial Processing Peptidase; Molecular Sequence Data; Multigene Family; Neurospora - enzymology; Polymerase chain reaction; Rats; Saccharomyces cerevisiae - enzymology; Sequence Homology, Amino Acid; Sequencing; Ungulates; Yeasts; Rat; Enzyme; Liver; Rodentia; Sequence alignment; Beta-Peptide chain; Primary structure; Molecular targeting; Vertebrata; Mitochondria; Mammalia; Complementary DNA; Endopeptidase; Metalloproteinase; Molecular cloning
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.90.11.5355

Most nuclearly encoded mitochondrial proteins are synthesized with amino-terminal leader peptides that are removed by the mitochondrial processing peptidase (MPP) after translocation. Earlier we reported cloning and sequencing of a cDNA for the larger subunit (MPP α subunit) of this enzyme from rat liver mitochondria. We have now completed the cloning and sequencing of a cDNA encoding the smaller subunit of the enzyme (MPP β subunit) from the same source. The cDNA consists of 1570 bp: 17 bp of 5'-untranslated sequence, 1467 bp of coding sequence, and 86 bp of 3'-untranslated sequence. The predicted protein consists of 489 amino acid residues, including a 45-amino acid leader peptide at the amino terminus and a 444-amino acid mature protein. The amino acid sequences of four tryptic peptides derived from purified MPP β subunit precisely match those predicted by the cDNA sequence, as does the predicted mature amino terminus. The amino-terminal sequence is typical of a mitochondrial leader peptide, with eight positively charged arginine residues and a single negatively charged aspartate residue. When the amino acid sequence of rat MPP β subunit is compared with sequences in the protein data bases, significant homology is found with the protease-enhancing protein of Neurospora crassa, the smaller subunit of MPP from Saccharomyces cerevisiae, and the core I protein of bovine ubiquinol:cytochrome c reductase. Lower homology is found with other members of a recently proposed class of endoproteases, which includes human insulinase and protease III from Escherichia coli.