Biochemistry (Moscow) (v.78, #8)
Protein biosynthesis in mitochondria by A. V. Kuzmenko; S. A. Levitskii; E. N. Vinogradova; G. C. Atkinson; V. Hauryliuk; N. Zenkin; P. A. Kamenski (855-866).
Translation, that is biosynthesis of polypeptides in accordance with information encoded in the genome, is one of the most important processes in the living cell, and it has been in the spotlight of international research for many years. The mechanisms of protein biosynthesis in bacteria and in the eukaryotic cytoplasm are now understood in great detail. However, significantly less is known about translation in eukaryotic mitochondria, which is characterized by a number of unusual features. In this review, we summarize current knowledge about mitochondrial translation in different organisms while paying special attention to the aspects of this process that differ from cytoplasmic protein biosynthesis.
Keywords: mitochondria; translation; ribosomes; translation factors
Regulation of activity of transcription factor NF-κB by synthetic oligonucleotides by V. G. Metelev; E. A. Kubareva; T. S. Oretskaya (867-878).
Eukaryotic dimeric nuclear factor-κB (NF-κB) is one of the main transcription factors that activate expression of genes, products of which play the key role in development of cardiovascular pathologies, carcinogenesis, and inflammatory and viral diseases. In this review, the main attention is given to modulation of the transcription factor NF-κB activity by antisense oligonucleotides and oligonucleotide decoys. Also, current concepts about interactions between NF-κB dimers and DNA and general problems that arise in experimental use of synthetic oligonucleotides in vivo are discussed.
Keywords: transcription factor NF-κB; modified oligonucleotides; antisense oligonucleotides; oligonucleotides decoys; aptamers
Expression of chicken CTCF gene in COS-1 cells and partial purification of CTCF protein by E. S. Kotova; I. V. Sorokina; S. B. Akopov; L. G. Nikolaev; E. D. Sverdlov (879-883).
The chicken gene for transcription factor CTCF was expressed in COS-1 mammalian cells. The CTCF protein containing polyhistidine tag was partially purified using metallo-affinity and ion-exchange chromatography. The expressed protein localized in the cell nucleus and was shown to be functionally active in the electrophoretic mobility shift assay and specifically interacted with anti-CTCF antibodies.
Keywords: transcription factor CTCF; expression in mammalian cells; COS-1
Targeted delivery of doxorubicin: Drug delivery system based on PAMAM dendrimers by N. G. Yabbarov; G. A. Posypanova; E. A. Vorontsov; O. N. Popova; E. S. Severin (884-894).
Polyamidoamine (PAMAM) dendrimers of the second generation (G2) are branched polymers containing 16 surface amino groups that allow them to be used as universal carriers on creating systems for drug delivery. G2 labeled with fluorescein isothiocyanate (FITC) efficiently bound with the surface of tumor cells at 4°C and was absorbed by the cells at 37°C. The covalent binding to G2-FITC of a vector protein, a recombinant fragment of the human alpha-fetoprotein receptor-binding domain (rAFP3D), increased the binding and endocytosis efficiency more than threefold. Covalent conjugates of G2 with doxorubicin (Dox) obtained by acid-labile linking of cis-aconitic anhydride (CAA) without the vector protein (G2-Dox) and with the vector protein rAFP3D (rAFP3D-G2-Dox) were accumulated by the tumor cells with high efficiency. However, a selective effect was observed only in rAFP3D-G2-Dox, which also demonstrated high cytotoxic activity against the human ovarian adenocarcinoma SKOV3 cells and low cytotoxicity against human peripheral blood lymphocytes. Based on these results, rAFP3D-G2 conjugate is promising for selective delivery of antitumor drugs.
Keywords: dendrimers; targeted drug delivery; endocytosis; alpha-fetoprotein; acid-labile linker; antitumor
Assay of insulator enhancer-blocking activity with the use of transient transfection by N. A. Smirnov; D. A. Didych; S. B. Akopov; L. G. Nikolaev; E. D. Sverdlov (895-903).
We used a transient transfection of cultured cells with linearized plasmids to analyze the enhancer-blocking activity of potential insulators including the standard cHS4 chicken beta-globin insulator and several DNA fragments selected from the human genome sequence. About 60–80% of the potential insulators do reveal the enhancer-blocking activity when probed by the transient transfection assay. The activity of different sequences is characterized by certain tissue specificity and by dependence on the orientation of the fragments relative to the promoter. Thus, the transfection model may be used for quantitative analysis of the enhancer-blocking activity of the potential insulators.
Keywords: human genome; gene expression regulation; insulator; enhancer
Comparison of oxygen consumption rates in minimally transformed BALB/3T3 and virus-transformed 3T3B-SV40 cells by E. I. Leznev; I. I. Popova; V. P. Lavrovskaja; Y. V. Evtodienko (904-908).
In the recent years, bioenergetics of tumor cells and particularly cell respiration have been attracting great attention because of the involvement of mitochondria in apoptosis and growing evidence of the possibility to diagnose and treat cancer by affecting the system of oxidative phosphorylation in mitochondria. In the present work, a comparative study of oxygen consumption in 3T3B-SV40 cells transformed with oncovirus SV40 and parental BALB/3T3 cells was conducted. Such fractions of oxygen consumption as “phosphorylating” respiration coupled to ATP synthesis, “free” respiration not coupled to ATP synthesis, and “reserve” or hidden respiration observed in the presence of protonophore were determined. Maximal respiration was shown to be only slightly decreased in 3T3B-SV40 cells as compared to BALB/3T3. However, in the case of certain fractions of cellular respiration, the changes were significant. “Phosphorylating” respiration was found to be reduced to 54% and “reserve” respiration, on the contrary, increased up to 160% in virus-transformed 3T3B-SV40 cells. The low rate of “phosphorylating” respiration and high “reserve” respiration indicate that under normal incubation conditions the larger part of mitochondrial respiratory chains of the virus-transformed cells is in the resting state (i.e. there is no electron transfer to oxygen). The high “reserve” respiration is suggested to play an important role in preventing apoptosis of 3T3B-SV40 cells.
Keywords: BALB/3T3 and 3T3B-SV403T3 cell cultures; respirometry; cellular respiration; inhibitors of oxidative phosphorylation; tumor cells; programmed cell death
Isolation and properties of flight muscle mitochondria of the bumblebee Bombus terrestris (L.) by M. Yu. Syromyatnikov; A. V. Lopatin; A. A. Starkov; V. N. Popov (909-914).
This report describes the isolation procedure and properties of tightly coupled flight muscle mitochondria of the bumblebee Bombus terrestris (L.). The highest respiratory control index was observed upon oxidation of pyruvate, whereas the highest respiration rates were registered upon oxidation of a combination of the following substrates: pyruvate + malate, pyruvate + proline, or pyruvate + glutamate. The respiration rates upon oxidation of malate, glutamate, glutamate + malate, or succinate were very low. At variance with flight muscle mitochondria of a number of other insects reported earlier, B. terrestris mitochondria did not show high rates of respiration supported by oxidation of proline. The maximal respiration rates were observed upon oxidation of α-glycerophosphate. Bumblebee mitochondria are capable of maintaining high membrane potential in the absence of added respiratory substrates, which was completely dissipated by the addition of rotenone, suggesting high amount of intramitochondrial NAD-linked oxidative substrates. Pyruvate and α-glycerophosphate appear to be the optimal oxidative substrates for maintaining the high rates of oxidative metabolism of the bumblebee mitochondria.
Keywords: insects; bumblebee; flight muscle; mitochondria; oxidative substrates; oxidative phosphorylation
Glycogen synthase kinase-3β is involved in C-reactive protein-induced endothelial cell activation by Shao-Jun Liu; Wei-Hua Liu; Yun Zhong; Shi-Ming Liu (915-919).
C-reactive protein (CRP) is a significant contributor to atherosclerosis and a powerful predictor of cardiovascular risk. The role of CRP in endothelial cell (EC) activation has been extensively investigated, but the underlying mechanisms have not been fully elucidated. The effect of glycogen synthase kinase-3β (GSK-3β) on CRP-induced EC activation was evaluated in this study. We observed that CRP decreased endothelial nitric oxide synthase (eNOS) activity during EC activation. CRP also activated GSK-3β by dephosphorylating its Ser9 level and reducing β-catenin protein expression in a time-dependent manner. We also found that the GSK-3β inhibitors TDZD-8 and SB415286 partially restored eNOS activity and suppressed the release of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 from ECs. These data provide new evidence for the involvement of GSK-3β in EC activation.
Keywords: GSK-3β; CRP; endothelial activation; eNOS; atherosclerosis
A straightforward experimental approach to expression, purification, refolding, and enzymatic analysis of recombinant dengue virus NS2B(H)-NS3pro protease by M. Junaid; C. Angsuthanasombat; J. E. S. Wikberg; N. Ali; G. Katzenmeier (920-924).
Dengue virus threatens around 2.5 billion people worldwide; about 50 million become infected every year, and yet no vaccine or drug is available for prevention and/or treatment. The flaviviral NS2B-NS3pro complex is indispensable for flaviviral replication and is considered to be an important drug target. The aim of this study was to develop a simple and generally applicable experimental strategy to construct, purify, and assay a highly active recombinant NS2B(H)-NS3pro complex that would be useful for high-throughput screening of potential inhibitors. The sequence of NS2B(H)-NS3pro was generated by overlap extension PCR (SOE-PCR) and cloned into the pTrcHisA vector. Hexahistidine-tagged NS2B(H)-NS3pro complex was expressed in E. coli predominantly as insoluble protein and purified to >95% purity by single-step immobilized metal affinity chromatography. SDS-PAGE followed by immunoblotting of the purified enzyme demonstrated the presence of the NS2B(H)-NS3pro precursor and its autocleavage products, NS3pro and NS2B(H), as 37, 21, and 10 kDa bands, respectively. Kinetic parameters, K m, k cat, and k cat/K m for the fluorophore-linked protease model substrate Ac-nKRR-amc were obtained using inner-filter effect correction. The kinetic parameters K m, k cat, and k cat/K m for Ac-nKRR-amc substrate were 100 μM, 0.112 s−1, and 1120 M−1·s−1, respectively. A simplified procedure for the cloning, overexpression, and purification of the NS2B(H)-NS3pro complex was applied, and a highly active recombinant NS2B(H)-NS3pro complex was obtained that could be useful for the design of high-throughput assays aimed at flaviviral inhibitor discovery.
Keywords: Dengue virus; NS2B(H)-NS3pro protease; purification; assay; substrate
Modulation of enzymatic activity of dengue virus nonstructural protein NS3 nucleoside triphosphatase/helicase by poly(U) by M. Junaid; C. Angsuthanasombat; J. E. S. Wikberg; N. Ali; G. Katzenmeier (925-932).
The nonstructural protein 3 (NS3) appears to be the most promising target for anti-flavivirus therapy because of its multiple enzymatic activities that are indispensable for virus replication. NS3 of dengue virus type 2 (DEN2) is composed of two domains, a serine protease in the N-terminal domain (NS3pro) and RNA-stimulated nucleoside triphosphatase (NTPase)/RNA helicase at the C-terminus (NS3h). NS3 plays an important role in viral replication and the coordinated regulation of all the catalytic activities in the full-length NS3 protein. In this study, a plasmid harboring the NS3 helicase domain (NS3h) was constructed by PCR. The 56.5 kDa NS3h protein was purified by metal-chelate affinity chromatography followed by renaturation, mediated by artificial chaperone-assisted refolding, which yielded the active helicase. NTPase activity was assayed with Malachite Green. The NTPase activity in the presence of poly(U) showed a higher turnover number (k cat) and a lower K m value than without poly(U). The activity increased approximately fourfold in the presence of polynucleotides. This indicates that NTPase activity of dengue NS3 can be stimulated by polynucleotides. A helicase assay based on internal fluorescence quenching was conducted using short internally quenched DNA oligonucleotides as substrates. Significant fluorescence signaling increase was observed in the absence of polynucleotides such as poly(U). No unwinding activity was observed with addition of poly(U). The approach we describe here is useful for the further characterization of substrate specificity and for the design of high-throughput assays aimed at discovery of inhibitors against NS3 NTPase/helicase activities.
Keywords: Dengue virus; NS3 protein; NTPase; helicase; assay; substrate; polynucleotide
Coordination in gene expression during atherogenesis by T. A. Shchelkunova; I. A. Morozov; P. M. Rubtsov; L. M. Samokhodskaya; I. A. Sobenin; A. N. Orekhov; A. N. Smirnov (933-945).
General tendencies in the regulation of gene expression during atherogenesis were investigated using correlation analysis for 34 mRNA species of several functional groups. The contents of mRNA were measured by quantitative PCR in samples of human aortal intima containing no lesions or atherosclerotic lesions of types I (initial lesions), II (fatty streaks), and Va (fibroatheromas). The coupling between mRNA contents in lesions and the same mRNAs in intact tissue was found to descend in the course of the disease progression. The data are in accordance with the opinion that successive morphologic types of atherosclerotic lesions correspond to steps of atherogenesis. In addition, the contents of individual mRNA species could correlate with each other within the given sample type, the extent of this coupling rising along with the disease progression. The exception from this rule was a collapse in coupling for several functional groups of mRNA in lesions of type I. This collapse could indicate special position of these lesions in pathogenesis. Statistically significant correlations between mRNAs found in samples of all four types comprised in total about 50% of all possible correlations. 66% of these correlations were conservative, i.e. observed in at least two sample types. By coupling-strength, the studied mRNAs could be divided into four clusters whose composition significantly varied along with the disease progression. The disease progression was also associated with decline in number of regulatory factors that determine coordination in expression of the analyzed genes.
Keywords: mRNA; PCR; gene expression; atherogenesis; aorta; correlation analysis
Polyphosphates and exopolyphosphatase activities in the yeast Saccharomyces cerevisiae under overexpression of homologous and heterologous PPN1 genes by M. A. Eldarov; M. V. Baranov; M. V. Dumina; A. A. Shgun; N. A. Andreeva; L. V. Trilisenko; T. V. Kulakovskaya; L. P. Ryasanova; I. S. Kulaev (946-953).
The role of exopolyphosphatase PPN1 in polyphosphate metabolism in fungi has been studied in strains of Saccharomyces cerevisiae transformed by the yeast PPN1 gene and its ortholog of the fungus Acremonium chrysogenum producing cephalosporin C. The PPN1 genes were expressed under a strong constitutive promoter of the gene of glycerol aldehyde-triphosphate dehydrogenase of S. cerevisiae in the vector pMB1. The yeast strain with inactivated PPN1 gene was transformed by the above vectors containing the PPN1 genes of S. cerevisiae and A. chrysogenum. Exopolyphosphatase activity in the transformant with the yeast PPN1 increased 28- and 11-fold compared to the mutant and parent PPN1 strains. The amount of polyphosphate in this transformant decreased threefold. Neither the increase in exopolyphosphatase activity nor the decrease in polyphosphate content was observed in the transformant with the orthologous PPN1 gene of A. chrysogenum, suggesting the absence of the active form of PPN1 in this transformant.
Keywords: polyphosphates; exopolyphosphatase; PPN1 gene; Saccharomyces cerevisiae ; Acremonium chrysogenum ; transformation
Expression of duodenase-like protein in epitheliocytes of Brunner’s glands in human duodenal mucosa by T. S. Zamolodchikova; I. T. Scherbakov; B. N. Khrennikov; E. V. Svirshchevskaya (954-957).
A duodenase, a protease structurally related to human cathepsin G, was found earlier in bovine duodenal mucosa. It was demonstrated that under the influence of duodenase an enteropeptidase zymogen is activated in vitro showing the possible participation of duodenase in the cascade of activation of digestive enzymes. To identify a duodenase functional analog in human duodenum, an immunofluorescence study of duodenal mucosa was conducted by confocal microscopy using antibodies to human cathepsin G and to bovine duodenase. The previously unknown place of synthesis and secretion of cathepsin G — Paneth cells located at the bottom of Lieberkuhn crypts — was revealed. Binding of cathepsin G-specific antibodies in a rough endoplasmic reticulum zone and in the cryptal duct was observed. Duodenase-specific immunofluorescence but not that of cathepsin G was found in the epitheliocytes and secretory ducts of Brunner’s glands, which are characteristic sites of duodenase biosynthesis in cattle. Binding of CD14-specific antibodies in the Brunner’s glands, where the antibodies co-localized with the antibodies to duodenase, was also demonstrated. These data indicate the presence of a protein immunologically similar to duodenase in the human duodenal mucosa. Our study demonstrated the absence of its colocalization with cathepsin G in Brunner’s glands.
Keywords: duodenase; cathepsin G; CD14; duodenum; Paneth cells; Brunner’s glands; immunolocalization; confocal microscopy
Escherichia coli signal peptidase recognizes and cleaves the signal sequence of α-amylase originating from Bacillus licheniformis by B. Malik; N. Rashid; N. Ahmad; M. Akhtar (958-962).
The gene encoding the α-amylase from Bacillus licheniformis was cloned, with and without the native signal sequence, and expressed in Escherichia coli, resulting in the production of the recombinant protein in the cytoplasm as insoluble but enzymatically active aggregates. Expression with a low concentration of the inducer at low temperature resulted in the production of the recombinant protein in soluble form in a significantly higher amount. The protein produced with signal sequence was exported to the extracellular medium, whereas there was no export of the protein produced from the gene without the signal sequence. Similarly, the α-amylase activity in the culture medium increased with time after induction in case of the protein produced with signal sequence. Molecular mass determinations by MALDI-TOF mass spectrometry and N-terminal amino acid sequencing of the purified recombinant α-amylase from the extracellular medium revealed that the native signal peptide was cleaved by E. coli signal peptidase between Ala28 and Ala29. It seems possible that the signal peptide of α-amylase from B. licheniformis can be used for the secretion of other recombinant proteins produced using the E. coli expression system.
Keywords: α-amylase; Bacillus licheniformis ; signal peptide