Process mitochondrial

Luciano, P., and Geli, V. (1996). The mitochondrial processing peptidase function and specificity. Experientia 52, 1077-1082. 

Song, M.-C., Shimokata, K, Kitada, S., Ogishima, T., and Ito, A. (1996). Role of basic amino acids in the cleavage of synthetic peptide substrate by mitochondrial processing peptidase./. Biochem.. (Tokyo) 120, 1163-1166. 

This zinc-dependent enzyme [EC 3.4.24.59] of the peptidase M3 family catalyzes the hydrolysis of a peptide bond such that there is a release of an N-terminal octa-peptide at the second stage of processing of some proteins imported into the mitochondrion. The natural substrates are precursor proteins that already have been processed by the mitochondrial processing peptidase. 

This a-helix is amphipathic, containing patches of positively charged and hydrophobic amino acids, respectively, on opposite surfaces of the theoretical cylinder. The presequence is usually processed by the mitochondrial processing peptidase (MPP) and the mature protein is sorted to either the matrix, or to the inner membrane if it bears a hydrophobic stop-transfer sequence. Some mitochondrial proteins, mostly destined to the membranes, do not have cleavable N-terminal presequences but have internal targeting signals that are not well characterized (Pfanner and Geissler 2001). 

Fig-i Mitochondrial protein import machinery as defined in S. cerevisiae. TOM translo-case of the outer mitochondrial membrane SAM sorting and assembly machinery TIM translocase of the inner mitochondrial membrane MIA mitochondrial IMS import and assembly machine PAM presequence translocase associated motor IMP inner membrane protease MPP mitochondrial processing peptidase. The numbers on the individual Tom, Sam, Tim or Pam components represent their approximate molecular masses in kDa. See text for mechanistic details. Adopted from Dolezal et al. 2006... 

Mitochondrial processing peptidase (J-MPP MSIISRY AVPQISKLSNGVRV() Dolezal et al. (2005)... 

The mitochondrial processing peptidase is an essential zinc-dependent met-allopeptidase (Yaffe et al. 1985 Luciano and Geli 1996 Gakh et al. 2002 Nomura et al. 2006). It cleaves the N-terminal presequence from precursors to matrix-targeted proteins, and from precursors destined for the inner mem-... 

Gabriel et al. (2007) Novel mitochondrial intermembrane space proteins as substrates of the MIA import pathway. J Mol Biol 365 612-620 Gakh O, Cavadini P, Isaya G (2002) Mitochondrial processing peptidases. Biochim Biophys Acta 1592 63-77... 

Nomura H, Athauda SB, Wada H, Maruyama Y, Takahashi K, Inoue H (2006) Identification and reverse genetic analysis of mitochondrial processing peptidase and the core protein of the cytochrome bcl complex of Caenorhabditis elegans, a model parasitic nematode. J Biochem (Tokyo) 139 967-979... 

After translocation into the mitosome, the N-terminal presequences of mitosomal proteins are cleaved off, most likely by a peptidase that is homologous to the mitochondrial processing peptidase (MPP). The MPP is a matrix-localized metallopeptidase with a zinc binding motif His-X-X-Glu-His that is conserved in the putative mitosomal processing peptidase reported in G. intestinalis (Dolezal et al. 2005). 

Mitochondria arise by division and growth of preexisting mitochondria. Because they synthesize only a few proteins and RNA molecules, they must import many proteins and other materials from the cytoplasm. A mitochondrion contains at least 100 proteins that are encoded by nuclear genes.50,50a The mechanisms by which proteins are taken up by mitochondria are complex and varied. Many of the newly synthesized proteins carry, at the N terminus, presequences that contain mitochondrial targeting signals51-53 (Chapter 10). These amino acid sequences often lead the protein to associate with receptor proteins on the outer mitochondrial membrane and subsequently to be taken up by the mitochondria. While the targeting sequences are usually at the N terminus of a polypeptide, they are quite often internal. The N-terminal sequences are usually removed by action of the mitochondrial processing peptidase (MPP) in... 

Cleavage at the 5 end of the 5.8S region requires RNase MRP, a relative of the RNase P that cleaves at the 5 ends of tRNAs (Fig. 28-10).525 547 MRP (mitochondrial processing protein) also cleaves primers for mitochondrial DNA replication. The importance of the enzyme is emphasized by the existence of a hereditary defect in the MRP RNA (Table 28-3) that causes abnormalities in bone, cartilage, hair, and the immune system.5473 Most bacterial rRNA genes have a tRNA gene in the position corresponding to that of 5.8S RNA... 

The author thinks that, possibly, a general layout of mitochondrial processes— accumulators of the chemical energy in the cell —may be composed. It will unite statements of both hypotheses and describe various consecutive events of mitochondrion operation. 

Modem biochemical investigations are mostly aimed at developing an entire approach to solving different problems and, hence, different biochemical reactions act as the stages of overall mitochondrial process, in which as is commonly said all affect all . Therefore, some bioenergetic reactions (or events) may be difficult or even impossible to understand outside the framework of the entire approach. Note also that such an approach has become just recently predominant in biochemical investigations. In its framework, the totality of... 

In this case, an analogy between the current idea about mitochondrial processes and common chemical phenomenon of chemical process conjugation on membrane catalysts seems to be correct. It should be remembered that at conjugation on membrane catalysts primary and secondary reactions are implemented on different sides of the membrane. The intermediate product of the primary reaction diffuses through the membrane catalyst wall to the other side, where it inductively effects the substrate transformation in the secondary reaction. Chemical reaction conjugation on membrane catalysts shows the principal possibility of inducing chemical reactions through the membrane [29],... 

Figure 3.4 Structural organization of chemical conjugation in mitochondrial processes.

All the above questions can be satisfactorily answered in the framework of the chemical conjugation concept, where the central place is dedicated to H+ ions—the conjugation intermediates. The author s hope that the concept of chemical conjugation of mitochondrial processes put forward will settle the various points between two common alternative hypotheses of biochemistry chemical conjugation and chemiosmosis [13]. 

The mitochondrial process displays an untypical, more likely unique, shape of chemical interference, characterized by the highest coherence form, when the phase shift equals 0. Such a shape of the interference pattern demonstrates high conformity of bioenergetic processes and, probably, the highest symmetry in synchronized reactions. Of course, the above-mentioned interaction between synchronous reactions is possible only at membrane analysis. 

Figure 3.8 Theoretical kinetic curves of the interference pattern for mitochondrial process in the absence of the phase shift.

Braun, H. P., Emmermann, M., Kruft, V., and Schmitz, U. K., 1992, The general mitochondrial processing peptidase from potato is an integral part of cytochrome c reductase of the respiratory chain, EMBO J. Il 3219n3227. 

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