Mitochondrial nucleic acids

Not all the cellular DNA is in the nucleus some is found in the mitochondria. In addition, mitochondria contain RNA as well as several enzymes used for protein synthesis. Interestingly, mitochond-rial RNA and DNA bear a closer resemblance to the nucleic acid of bacterial cells than they do to animal cells. For example, the rather small DNA molecule of the mitochondrion is circular and does not form nucleosomes. Its information is contained in approximately 16,500 nucleotides that func-tion in the synthesis of two ribosomal and 22 transfer RNAs (tRNAs). In addition, mitochondrial DNA codes for the synthesis of 13 proteins, all components of the respiratory chain and the oxidative phosphorylation system. Still, mitochondrial DNA does not contain sufficient information for the synthesis of all mitochondrial proteins most are coded by nuclear genes. Most mitochondrial proteins are synthesized in the cytosol from nuclear-derived messenger RNAs (mRNAs) and then transported into the mito-chondria, where they contribute to both the structural and the functional elements of this organelle. Because mitochondria are inherited cytoplasmically, an individual does not necessarily receive mitochondrial nucleic acid equally from each parent. In fact, mito-chondria are inherited maternally. 

Mitochondria were first observed by R. Altmann in 1890. He named them bioblasts, because he speculated that they and chloroplasts (the green chlorophyll-containing organelles of plants) might be intracellular symbionts that arose from bacteria and algae, respectively. This idea lay in disrepute until the recent discovery of mitochondrial nucleic acids. 

D. Role of Mitochondrial Nucleic Acid and Protein Synthesis... 

Ability of Mouse Blastocysts to Form Viable Fetuses after in vitro Cultivation (2-4 Cell Stage Blastocyst) in the Presence of Inhibitors op Mitochondrial Nucleic Acid or Protein Synthesis"... 

Fig. 16. Coding of mitochondrial nucleic acids and proteins by n DNA and mt DNA and possible regulatory mechanisms.

Zinc. The 2—3 g of zinc in the human body are widely distributed in every tissue and tissue duid (90—92). About 90 wt % is in muscle and bone unusually high concentrations are in the choroid of the eye and in the prostate gland (93). Almost all of the zinc in the blood is associated with carbonic anhydrase in the erythrocytes (94). Zinc is concentrated in nucleic acids (90), and found in the nuclear, mitochondrial, and supernatant fractions of all cells. 

Muratovska a., Lightowlers R. N., Taylor R.W., Turnbull D.M., Smith R.A. J., WiLCE J.A., Martin S.W., Murphy M.P. Targeting peptide nucleic acid (PNA) oligomers to mitochondria within cells by conjugation to lipophilic cations implications for mitochondrial DNA replication, expression and disease. Nucleic Acids Res. 2001 29 1852-1863. 

Nucleic acids are not the only biomolecules susceptible to damage by carotenoid degradation products. Degradation products of (3-carotene have been shown to induce damage to mitochondrial proteins and lipids (Siems et al., 2002), to inhibit mitochondrial respiration in isolated rat liver mitochondria, and to induce uncoupling of oxidative phosphorylation (Siems et al., 2005). Moreover, it has been demonstrated that the degradation products of (3-carotene, which include various aldehydes, are more potent inhibitors of Na-K ATPase than 4-hydroxynonenal, an aldehydic product of lipid peroxidaton (Siems et al., 2000). 

Scharfe C et al. MITOP, the mitochondrial proteome database 2000 update. Nucleic Acids Res 2000 28 155-158. Molloy MP et al. Establishment of the human reflex tear two-dimensional polyacrylamide gel electrophoresis reference map new proteins of potential diagnostic value. Electrophoresis 1997 18 2811-2815. 

Other systems like electroporation have no lipids that might help in membrane sealing or fusion for direct transfer of the nucleic acid across membranes they have to generate transient pores, a process where efficiency is usually directly correlated with membrane destruction and cytotoxicity. Alternatively, like for the majority of polymer-based polyplexes, cellular uptake proceeds by clathrin- or caveolin-dependent and related endocytic pathways [152-156]. The polyplexes end up inside endosomes, and the membrane disruption happens in intracellular vesicles. It is noteworthy that several observed uptake processes may not be functional in delivery of bioactive material. Subsequent intracellular obstacles may render a specific pathway into a dead end [151, 154, 156]. With time, endosomal vesicles become slightly acidic (pH 5-6) and finally fuse with and mature into lysosomes. Therefore, polyplexes have to escape into the cytosol to avoid the nucleic acid-degrading lysosomal environment, and to deliver the therapeutic nucleic acid to the active site. Either the carrier polymer or a conjugated endosomolytic domain has to mediate this process [157], which involves local lipid membrane perturbation. Such a lipid membrane interaction could be a toxic event if occurring at the cell surface or mitochondrial membrane. Thus, polymers that show an endosome-specific membrane activity are favorable. 

A molecular entity consisting of two or more polymeric rings interlinked together but not covalently bonded to each other. Mitochondrial DNA are known to form catenated structures consisting of two interlinked nucleic acid circles (i.e., a [2]catenane). 

Dye oxidation (e.g., tetrazolium reductase activity with 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide, MTT 2-[4-iodophenyl]-3-[4-nitrophenyl]-5-[2,4-disulfophenyl]-2H tetrazolium monosodium salt, WST-1 3- (4,5 -carboxymethoxyphenyl) -2-(4-sulfophenyl)-2 H-tetra-zolium, MTS 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide inner salt, XTT 2,2 -di-p-nitrophenyl-5,5 -diphenyl-3,3 -(3,3 -dimethoxy-4,4 -diphe-nylenej-ditetrazolium chloride, NET), Alamar blue assays, ATP concentration (e.g., luciferase assay), oxygen consumption (e.g., oxygen electrodes, phosphorescent oxygen-sensitive dyes), mitochondrial protein and nucleic acid synthesis mitochondrial mass (e.g., mitotracker dyes) mitochondrial membrane potential (e.g., tetramethylrho-damine methyl ester, TMRM tetramethylrhodamine ethyl ester, TMRE)... 

Mechanism of Action A systemic anti-infective that inhibits the mitochondrial electron-transport system at the cytochrome bcl complex (Complex 111), which interrupts nucleic acid and adenosine triphosphate synthesis. Therapeutic Effect Antiprotozoal and antipneumocystic activity. 

The sequences of all three pieces of RNA in the E. coli ribosomes are known as are those from many other species. These include eukaryotic mitochondrial, plas-tid, and cytosolic rRNA. From the sequences alone, it was clear that these long molecules could fold into a complex series of hairpin loops resembling those in tRNA. For example, the 16S rRNA of E. coli can fold as in Fig. 29-2A and eukaryotic 18S RNA in a similar way (Fig. 29-4).38/39/67 69 The actual secondary structures of 16S and 18S RNAs, within the folded molecules revealed by X-ray crystallography, are very similar to that shown in Fig. 29-2A. Ribosomal RNAs undergo many posttranscriptional alterations. Methylation of 2 -hydroxyls and of the nucleic acid bases as well as conversion to pseudouridines (pp. 1638-1641) predominate over 200 modifications, principally in functionally important locations that have been found in human rRNA.69a... 

Boore, J.L. (1999) Animal mitochondrial genomes. Nucleic Acids Research 27, 1767-1780. 

Jameson, D., Gibson, A.P., Hudelot, C. and Higgs, P.G. (2003) OGRe a relational database for comparative analysis of mitochondrial genomes. Nucleic Acids Research 31, 202-206. 

Zurita, M., Bieber, D., Ringold, C. and Mansour, T.E. (1 988) cDNA cloning and gene characterization of the mitochondrial large subunit (LSU) rRNA from the liver fluke Fasciola hepatica. Evidence of heterogeneity in the fluke mitochondrial genome. Nucleic Acids Research 16, 7001-7012. 

Taylor, R.W., Chinnery, P.P., Turnbull, D M. and Lightowlers, R.N. (1997) Selective inhibition of mutant human mitochondrial DNA replication in vitro by peptide nucleic acids. Nature Genetics, 15, 212-215. 

T8. Taylor, R. W., Wardell, T. M., Connolly, B. A., Turnbull, D. M., and Lightowlers, R. N., Linked oligodeoxynucleotides show binding cooperativity and can selectively impair replication of deleted mitochondrial DNA templates. Nucleic Acids Res. 29, 3404-3412 (2001). 

Y2. Yasukawa, T., Hino, N., Suzuki, T., Watanabe, K., Ueda, T., and Ohta, S., A pathogenic point mutation reduces stability of mitochondrial mutant tRNAIle. Nucleic Acids Res. 28, 3779-3784 (2000). 

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