Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.24.64 (MPP)
 1,876 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A number of nuclearly encoded mitochondrial protein precursors that are transported into the matrix and inner membrane are cleaved in two sequential steps by two distinct matrix peptidases, mitochondrial processing peptidase (MPP) and mitochondrial intermediate peptidase (MIP). We have isolated and purified MIP from rat liver mitochondrial matrix. The enzyme, purified 2250-fold, is a monomer of 75 kDa and cleaves all tested mitochondrial intermediate proteins to their mature forms. About 20% of the final MIP preparation consists of equimolar amounts of two peptides of 47 kDa and 28 kDa, which are apparently the products of a single cleavage of the 75 kDa protein. These peptides are not separable from the 75 kDa protein, nor from each other, under any conditions used in the purification. The peptidase has a broad pH optimum between pH 6.6 and 8.9 and is inactivated by N-ethylmaleimide (NEM) and other sulfhydryl group reagents. The processing activity is divalent cation-dependent; it is stimulated by manganese, magnesium or calcium ions and reversibly inhibited by EDTA. Zinc, cobalt and iron strongly inhibit MIP activity. This pattern of cation dependence and inhibition is not clearly consistent with that of any known family of proteases.
 ...
PMID:Rat liver mitochondrial intermediate peptidase (MIP): purification and initial characterization. 132 90

Transport of nuclear-encoded precursor proteins into mitochondria includes proteolytic cleavage of amino-terminal targeting sequences in the mitochondrial matrix. We have isolated the processing activity from Neurospora crassa. The final preparation (enriched ca. 10,000-fold over cell extracts) consists of two proteins, the matrix processing peptidase (MPP, 57 kd) and a processing enhancing protein (PEP, 52 kd). The two components were isolated as monomers. PEP is about 15-fold more abundant in mitochondria than MPP. It is partly associated with the inner membrane, while MPP is soluble in the matrix. MPP alone has a low processing activity whereas PEP alone has no apparent activity. Upon recombining both, full processing activity is restored. Our data indicate that MPP contains the catalytic site and that PEP has an enhancing function. The mitochondrial processing enzyme appears to represent a new type of "signal peptidase," different from the bacterial leader peptidase and the signal peptidase of the endoplasmic reticulum.
 ...
PMID:Mitochondrial protein import: identification of processing peptidase and of PEP, a processing enhancing protein. 296 9

Two proteins co-operate in the proteolytic cleavage of mitochondrial precursor proteins: the mitochondrial processing peptidase (MPP) and the processing enhancing protein (PEP). In order to understand the structure and function of this novel peptidase, we have isolated mutants of Saccharomyces cerevisiae which were temperature sensitive in the processing of mitochondrial precursor proteins. Here we report on the mif2 mutation which is deficient in MPP. Mitochondria from the mif2 mutant were able to import precursor proteins, but not to cleave the presequences. The MPP gene was isolated. MPP is a hydrophilic protein consisting of 482 amino acids. Notably, MPP exhibits remarkable sequence similarity to PEP. We speculate that PEP and MPP have a common origin and have evolved into two components with different but mutually complementing functions in processing of precursor proteins.
 ...
PMID:The processing peptidase of yeast mitochondria: the two co-operating components MPP and PEP are structurally related. 306 97

Nuclear-encoded proteins targeted to the chloroplast are typically synthesized with N-terminal transit peptides which are proteolytically removed upon import. Structurally related proteins of 145 and 143 kDa copurify with a soluble chloroplast processing enzyme (CPE) that cleaves the precursor for the major light-harvesting chlorophyll a/b binding protein and have been implicated in the maturation of the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase and acyl carrier protein. The 145- and 143-kDa proteins have not been found as a heterodimer and thus may represent functionally independent isoforms encoded by separate genes. Here we describe the primary structure of a 140-kDa polypeptide encoded by cDNAs isolated by using antibodies raised against the 145/143-kDa doublet. The 140-kDa polypeptide contains a transit peptide, and strikingly, a His-Xaa-Xaa-Glu-His zinc-binding motif that is conserved in a recently recognized family of metalloendopeptidases, which includes Escherichia coli protease III, insulin-degrading enzyme, and subunit beta of the mitochondrial processing peptidase. Identity of 25-30%, concentrated near the N terminus of the 140-kDa polypeptide, is found with these proteases. Expression of CPE in leaves is not light dependent. Indeed, transcripts are present in dark-grown plants, and the 145/143-kDa doublet and proteolytic activity are both found in etioplasts, as well as in root plastids. Thus, CPE appears to be a necessary component of the import machinery in photosynthetic and nonphotosynthetic tissues, and it may function as a general stromal processing peptidase in plastids.
 ...
PMID:A chloroplast processing enzyme involved in precursor maturation shares a zinc-binding motif with a recently recognized family of metalloendopeptidases. 763 64

The bc1-complex (EC 1.10.2.2.) from Triticum aestivum L. was purified by cytochrome-c affinity chromatography and gel filtration using either etiolated seedlings or wheat-germ extract as starting material. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the isolated enzyme revealed ten bands, which were analysed by immunoblotting and direct amino-acid sequencing. The enzyme from wheat is the first bc1-complex that is reported to contain four core proteins (55.5, 55.0, 51.5 and 51.0 kDa). In addition, the wheat bc1-complex comprises cytochrome b (35 kDa), cytochrome c1 (33 kDa) the "Rieske" iron-sulphur protein (25 kDa) and three small subunits < 15 kDa. This composition differs from the one reported in fungi, mammals and potato. Partial sequence determination of the large subunits suggests that the 55.5- and 55.0-kDa-proteins represent the beta-subunit of the general mitochondrial processing peptidase, and the 51.5- and 51.0-kDa proteins the alpha-subunit of this enzyme. The bc1-complex from wheat efficiently processes mitochondrial precursor proteins as shown in an in-vitro processing assay. In control experiments the isolated bc1-complexes from potato, yeast, Neurospora and beef, all purified by the same isolation procedure, were also tested for processing activity. Only the protein complexes from plants contain the general mitochondrial processing peptidase. The composition of the wheat bc1-complex sheds new light on the co-evolution of the processing peptidase and the middle segment of the respiratory chain.
 ...
PMID:The general mitochondrial processing peptidase from wheat is integrated into the cytochrome bc1-complex of the respiratory chain. 776 45

Cytochrome c reductase from potato is a bifunctional protein complex located in the inner mitochondrial membrane, which is involved in respiratory electron transport and processing of mitochondrial precursor proteins. The three largest subunits of the complex share the highest degree of sequence identity with the alpha- and beta-subunits of the soluble processing peptidase (MPP) from fungi and mammals. Evidence is provided that another substoichiometric polypeptide of the cytochrome c reductase complex resembles the alpha-subunit of MPP. A cDNA clone corresponding to the second alpha-MPP protein (alpha-II MPP) encodes a polypeptide of 504 amino acids which is 84% identical to alpha-I MPP. The two different alpha-MPP polypeptides have similar sizes on SDS-polyacrylamide gels but can be distinguished with an antibody raised against a decapeptide that is specific for alpha-II MPP. The presequences of both alpha-subunits of MPP are proteolytically removed by the integrated processing enzyme complex indicating that it acts on the targeting signals of its own precursor proteins. Gene-specific oligonucleotides reveal that the genes encoding alpha-subunit I and alpha-subunit II of MPP are differentially expressed in all tissues analysed but the transcript levels do not vary between tissues.
 ...
PMID:The mitochondrial processing peptidase from potato: a self-processing enzyme encoded by two differentially expressed genes. 781 32

We examined the structural characteristics of the extension peptides responsible for the recognition by the mitochondrial processing peptidase by using preadrenodoxin, which has a long extension peptide of 58 amino acid residues, as the substrate. The deletion of various parts of the extension peptide of pre-adrenodoxin indicated that more than 40 amino acid residues and the presence of basic amino acid residues in the distal portion (20-40 amino acid residues upstream of the cleavage site) were necessary for the recognition of the precursor by the peptidase. The processing of preadrenodoxin was strongly inhibited by the synthetic peptide corresponding to the middle portion of the extension peptide, whereas the peptide corresponding to the amino-terminal portion exhibited weak inhibition of the processing. The replacement of arginine residues in the middle portion of the extension peptide with neutral amino acids resulted in a great decrease in the processing. We conclude that basic amino acids at a position distal to the cleavage site are necessary for the recognition of the precursor proteins by the processing peptidase and that basic amino acids required for the mitochondrial targeting and those for the recognition by the peptidase are separately located in the extension peptide of pre-adrenodoxin.
 ...
PMID:Structural requirement for recognition of the precursor proteins by the mitochondrial processing peptidase. 792 39

The mitochondrial processing peptidase (MPP) of Neurospora crassa is constituted by an alpha- and a beta-subunit. We have purified alpha-MPP after expression in Escherichia coli while beta-MPP was purified from mitochondria. A fusion protein between precytochrome b2 and mouse dihydrofolate reductase was expressed in E. coli, and the purified protein was used as substrate for MPP. Both subunits of MPP are required for processing. MPP removes the matrix targeting signal of cytochrome b2 by a single cut, and the resulting presequence peptide is 31 amino acid residues in length. It acts as a competitive inhibitor of processing but has a approximately 30-fold lower affinity for MPP than the preprotein. Competition assays show that MPP recognizes the COOH-terminal portion of the presequence of cytochrome b2 rather than the NH2-terminal part which has the potential to form an amphiphilic helix. Substitution of arginine in position -2 of the matrix targeting sequence of cytochrome b2 prevents processing but not import of a chimeric precursor. Substitution of the tyrosyl residue in position +1 also prevents processing, indicating that MPP interacts with sequences COOH-terminal to the cleavage site. Non-cleavable preprotein is still recognized by MPP. Our data suggest that processing peptidase and import machinery recognize distinct structural elements in preproteins which, however, can be overlapping.
 ...
PMID:Characterization of the mitochondrial processing peptidase of Neurospora crassa. 810 71

Cytosol-synthesized chloroplast and mitochondrial precursor proteins are proteolytically processed after import by highly specific, metal-dependent soluble enzymes: the stromal processing peptidase (SPP) and the matrix processing peptidase (MPP), respectively. We have used in vitro processing assays to compare the reaction specificities of highly purified preparations of pea SPP and Neurospora crassa MPP, both of which are unable to cleave a variety of 'foreign' proteins. We show that SPP can cleave all five mitochondrial precursor proteins tested, namely cyclophilin, the beta subunit of the F1-ATPase complex, the Rieske FeS protein, the alpha-MPP subunit and cytochrome b2. In contrast, MPP is unable to cleave any chloroplast precursor proteins tested. Several of the mitochondrial precursor proteins are cleaved more efficiently by SPP than are many authentic chloroplast precursor proteins but, in each case, cleavage takes place at a site or sites which are N-terminal to the authentic MPP site; pre-cyclophilin is cleaved 5 residues upstream of the MPP site and the precursor of the beta subunit of the F1-ATPase complex is cleaved at sites 5 and 12 residues upstream. We discuss the implications of these data for the SPP reaction mechanism.
 ...
PMID:Efficient but aberrant cleavage of mitochondrial precursor proteins by the chloroplast stromal processing peptidase. 816 39

A novel Saccharomyces cerevisiae mutant, unable to grow in the presence of 12.5 mM EGTA, was isolated by replica plating. The phenotype of the mutant is caused by a single amino acid change (Gly149 to Arg) in the essential yeast gene CDC1. The mutant could be suppressed by overexpression of the SMF1 gene, which was isolated as an extragenic high-copy suppressor. The SMF1 gene codes for a highly hydrophobic protein and its deletion renders the yeast cells sensitive to low manganese concentration. In accordance with this observation, the smf1 null mutant exhibits reduced Mn2+ uptake at micromolar concentrations. Using a specific antibody, we demonstrated that Smf1p is located in the yeast plasma membrane. These results suggest that Smf1p is involved in high-affinity Mn2+ uptake. This assumption was also tested by overexpressing the SMF1 gene in the temperature-sensitive mutant of the mitochondrial processing peptidase (MAS1). SMF1 overexpression as well as addition of 1 mM Mn2+ to the growth medium complemented this mutation. This also suggests that in vivo Mas1p is a manganese-dependent peptidase. The yeast Smf1p resembles a protein from Drosophila and mammalian macrophages. The latter was implicated in conferring resistance to mycobacteria. A connection between Mn2+ transport and resistance or sensitivity to mycobacteria is discussed.
 ...
PMID:A yeast manganese transporter related to the macrophage protein involved in conferring resistance to mycobacteria. 864 35


1 2 3 4 5 Next >>