Effect of natural and genetically modified rhizospheric Pseudomonas aureofaciens bacteria on accumulation of arsenic by plants

Gene constructions rendering bacteria resistant to arsenic and capable of dissolving phosphates and/or arsenates were created by cloning ars operon and the gene of citrate synthase from a chromosome of the strain Pseudomonas aeruginosa PAO1. Genetically modified variants of the strain Pseudomonas aureofaciens BS1393 have been constructed, which are resistant to high concentrations of arsenic and dissolve poorly soluble phosphates and/or arsenates. Recombinant strains P. aureofaciens BS1393(pUCP22::arsRBC) and P. aureofaciens BS1393(pUCP22::gltA) exerted positive effects on the survival of sorgo (Sorghum saccharatum L.) and its ability to accumulate arsenic.     

Characteristics of rhamnan isolated from preparations of Pseudomonas aeruginosa lipopolysaccharides

A polysaccharide isolated from the degraded lipopolysaccharides of P. aeruginosa serogroup O7 (Lányi--Bergan classification) was characterized by liquid chromatography, acid hydrolysis, and 1H and 13C NMR spectroscopy. It has molecular mass 15,000 and represents mainly a rhamnan of the structure----2)-alpha-D-Rha-(1----3)-alpha-D-Rha-(1----3)-alpha-D-Rha-(1 ----, identical to the structure of O-specific polysaccharides of Pseudomonas aeruginosa pvs morsprunorum and cerasi. Some minor constituents, such as glucose, mannose, an unknown sugar, and phosphate, are found in the polysaccharide preparation as well. Distribution of the rhamnan in some other P. aeruginosa serogroups is discussed and its identity to the common polysaccharide antigen of P. aeruginosa is suggested.     

The use of p53 as a tool for human cancer therapy

The p53 tumor suppressor is a central component of a system that reinforces genetic stability of somatic cells in animals and humans. Inactivation of this gene occurs virtually in every cancer case, which eliminates results in further rapid accumulation of additional mutations leading to progression of a cancer cell toward more malignant phenotype. The mechanisms of p53 inhibition in cancer include point mutations leading to accumulation of inactive protein, deletion of the whole gene, or its portion, alteration in the genes involved in regulation of activity of p53, and defects in the genes controlled by p53. In addition, oncogenic viruses encode specialized proteins that are entitled to modify p53 functions in order to provide optimal condition for replication of viral genome. These viral proteins play central role in viral carcinogenesis, including 95% of cases of cervical carcinoma in women. The approacheas to restoration of p53 activity depend on particular type of alteration within the p53 pathway. In some cases an effective mean would be introduction of exogenous p53, particularly with the use of adenoviral vectors. There are also approaches in development that target reactivation of mutant proteins, or suppress natural inhibitors of p53. The review summarizes various schemes for therapy and prevention of cancer that are based on our knowledge of the p53 gene functions. Potential usefulness of the approaches for practical applications is discussed.     

The interaction of NS3 protein of hepatitis C virus with polymethylen derivatives of nucleic bases

NS3 protein of hepatitis C virus plays the key role in the virus functioning. It possesses three enzymatic activities, namely protease activity, associated with N-terminal domain of the protein, and helicase/NTPase activities specific for C-terminal domain. Here, the effect of some polimethylenic derivatives of the nucleic bases on helicase and ATPase enzyme activities has been studied. Several of compounds tested displayed inhibitory activity towards NS3 helicase. However, most compounds demonstrated strong activating effect on ATPase activity of the enzyme as well as several other ATPases. The ATPase activating mechanism was not described earlier. The activation potency of the compounds depended on substrate/activator concentration ratio, and was maximal at the 1000:1. The activation mechanism scheme that allows us to explain phenomena observed is proposed.     

Rhizosphere strain of <Emphasis Type="Italic">Pseudomonas chlororaphis</Emphasis> capable of degrading naphthalene in the presence of cobalt/nickel

Combination of genetic systems of degradation of polyaromatic hydrocarbons, resistance to heavy metals, and promotion of plant growth/protection is one of the approaches to the creation of polyfunctional strains for phytoremediation of soils after co-contamination with organic pollutants and heavy metals. A plant-growth-promoting rhizosphere strain Pseudomonas chlororaphis PCL1391 (pBS216^*, pBS501) has been obtained, in which the nah operon of plasmid pBS216 provides naphthalene biodegradation and the cnr-like operon of plasmid pBS501 provides resistance to cobalt and nickel due to the extrusion of heavy metal cations from the cells. In the presence of 100 μM of nickel, the viability, growth rate, and naphthalene biodegradation efficiency of the resistant strain PCL1391 (pBS216^*, pBS501) were much higher as compared with the sensitive PCL1391 (pBS216). During the growth of the resistant strain, in contrast to the sensitive strain, nickel (100 μM) had no inhibiting effect on the activity of the key enzymes of naphthalene biodegradation. Original Russian Text ? T.V. Siunova, T.O. Anokhina, A.V. Mashukova, V.V. Kochetkov, A.M. Boronin, 2007, published in Mikrobiologiya, 2007, Vol. 76, No. 2, pp. 212–218.     

Block-synthesis of higher oligosaccharides: Synthesis of hexa- and nona-saccharide fragments of the o-antigenic polysaccharide of Salmonella newington

Successive condensation of derivatives of the trisaccharide, biological repeating-unit of the O-antigenic polysaccharide of Salmonella newington, followed by removal of protecting groups, has given the hexa- and nona-saccharides. The structures of these oligosaccharides were confirmed chemically and by ¹³C-n.m.r. spectroscopy.     

Effect of deoxynojirimycin derivatives on morphogenesis of hepatitis C virus

Viral hepatitis C is a dangerous, widespread human disease. The choice of drugs for treatment of chronic hepatitis C virus (HCV) infection is limited, and prophylactic vaccines do not exist. Thus, the development of new antiviral strategies and substances is an issue of great importance. The targeting of viral morphogenesis might be used as an alternative approach to existing strategies of HCV blocking. The glycosylation of viral envelope proteins is an important step of viral particle morphogenesis, which determines the correct assembly of HCV virions. Derivatives of a glucose analog deoxynojirimycin (DNJ) act as an α-glucosidase inhibitor and can impair the assembly of structural proteins and HCV particle formation. In the present work, the effects of alkylated DNJ derivatives, N-pentyl-DNJ and N-benzyl-DNJ, on HCV morphogenesis were studied in a model system of insect cells that produce three viral structural proteins with the formation of virus-like particles. It was shown that DNJ derivatives impair the intracellular N-glycosylation of HCV envelope glycoproteins. At the concentration of 1 mM, these substances cause an increase in the levels of gpE1 and gpE2 glycoproteins and a decrease in their electrophoretic mobility, apparently due to the inhibition of α-glucosidase in the endoplasmic reticulum and the accumulation of hyperglycosylated N-glycans in HCV glycoproteins. The interaction of the latter with calnexin results in the formation of unproductive dimers and blocks the productive assembly of virus-like particles.     

Effect of Wild and Genetically Modified Rhizosphere Bacteria Pseudomonas aureofaciens on the Accumulation of Arsenic by Plants

Gene constructions rendering recombinant bacteria resistant to arsenic and increasing their ability to dissolve soil phosphates and/or arsenates were created by cloning the ars operon and the gene of citrate synthase from a chromosome of the strain Pseudomonas aeruginosa PA01. Genetically modified variants of the strain Pseudomonas aureofaciens BS1393 have been constructed that are resistant to high concentrations of arsenic and dissolve poorly soluble phosphates and/or arsenates. The recombinant strains P. aureofaciens BS1393(pUCP22::arsRBC) and P. aureofaciens BS1393(pUCP22::gltA) exerted positive effects on the survival of sorgo (Sorghum saccharatum L.) and its ability to accumulate arsenic.