ADP ribosylation adapts an ER chaperone response to short-term fluctuations in unfolded protein load

Gene expression programs that regulate the abundance of the chaperone BiP adapt the endoplasmic reticulum (ER) to unfolded protein load. However, such programs are slow compared with physiological fluctuations in secreted protein synthesis. While searching for mechanisms that fill this temporal gap in coping with ER stress, we found elevated levels of adenosine diphosphate (ADP)-ribosylated BiP in the inactive pancreas of fasted mice and a rapid decline in this modification in the active fed state. ADP ribosylation mapped to Arg470 and Arg492 in the substrate-binding domain of hamster BiP. Mutations that mimic the negative charge of ADP-ribose destabilized substrate binding and interfered with interdomain allosteric coupling, marking ADP ribosylation as a rapid posttranslational mechanism for reversible inactivation of BiP. A kinetic model showed that buffering fluctuations in unfolded protein load with a recruitable pool of inactive chaperone is an efficient strategy to minimize both aggregation and costly degradation of unfolded proteins.     

Synthesis and Cytotoxic Activity of a Number of Functionalized 2,3-Allenoates

Russian Journal of Bioorganic Chemistry - A series of new functionalized allenoates has been synthesized, and their cytotoxic effect has been studied against the tumor cell line (HepG2 and Jurkat)...     

Reversible change in thiol redox status of the insulin receptor alpha-subunit in intact cells

In this study, we used maleimidobutyrylbiocytin to examine possible alteration that may occur in the redox state of the insulin receptor (IR) sulfhydryl groups in response to reduced glutathione (GSH) or N-acetyl-L-cysteine (NAC). Short-term treatment of intact cells expressing large numbers of IR with GSH or NAC led to a rapid and reversible reduction of IR alpha-subunit disulfides, without affecting the receptor beta-subunit thiol reactivity. The overall integrity of the oligomeric structure of IR was maintained, indicating that neither class I nor class II disulfides were targeted by these agents. Similar findings were obtained in cells transfected with IR mutants lacking cysteine524, one of the class I disulfides that link the two IR alpha-subunits. Membrane-associated thiols did not participate in GSH- or NAC-mediated reduction of IR alpha-subunit disulfides. No difference in insulin binding was observed in GSH-treated cells; however, ligand-mediated increases in IR autophosphorylation, tyrosine phosphorylation of cellular substrates, and dual phosphorylation of the downstream target mitogen-activated protein kinase were inhibited at concentrations of GSH (10 mM or greater) that yielded a significant increase in IR alpha-subunit thiol reactivity. GSH did not affect IR signaling in the absence of insulin. Our results provide the first evidence that the IR alpha-subunit contains a select group of disulfides whose redox status can be rapidly altered by the reducing agents GSH and NAC.     

A comparison of the immune response induced by DNA or by an inactivated vaccine against tick-borne encephalitis

BALB/c mice were immunized with recombinant plasmid DNA pSVK3-ENS1 and pcDNAI-NS3 containing, respectively, genes E-NS1 and NS3 of tick-borne encephalitis (TBE) virus. Antibodies to TBE virus proteins were detected in the blood sera of the immunized animals by the method of the enzyme immunoassay. Though the titers of virus-specific antibodies in the sera of mice immunized with protein vaccines exceeded those registered after immunization with DNA vaccines, essential protective immunity was observed after the use of both vaccines.     

The circadian dynamics of the attacks of the synanthropic population of Culex pipiens molestus mosquitoes at the Staraia Russa Health Resort

The diurnal biting activity of Culex pipiens molestus in rooms of populated houses was studied in August 1998. The highest activity was recorded at 3.00-4.00 a. m., when 25-30 females attacked one volunteer rer 10 minutes.     

Stability of Recombinant Plasmids in Transgenic Microorganisms under Different Environmental Conditions

The copy number of R plasmids weakly depends on the selective pressure of the respective antibiotic but does depend on the physiology of the host species and the type of plasmids and cloned genes, whose expression leads to a further load on the biosynthetic apparatus of cells. The last factor is critical in the maintenance of recombinant plasmids in transgenic microorganisms.     

Structural Characterization and Chemical Classification of Some Bryophytes Found in Latvia

Bryophytes are the second largest taxonomic group in the plant kingdom; yet, studies conducted to better understand their chemical composition are rare. The aim of this study was to characterize the chemical composition of bryophytes common in Northern Europe by using elemental, spectral, and non‐destructive analytical methods, such as Fourier transform IR spectrometry (FT‐IR), solid‐phase ¹³C‐NMR spectrometry, and pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS), for the purpose of investigating their chemotaxonomic relationships on the basis of chemical‐composition data. The results of all these analyses showed that bryophytes consist mainly of carbohydrates. Judging by FT‐IR spectra, the OH groups in combination of C? O groups were the most abundant groups. The ¹³C‐NMR spectra provided information on the presence of such compounds as phenolics and lipids. It was found that the amount of phenolic compounds in bryophytes is relatively small. This finding definitely confirmed the absence of lignin in the studied bryophytes. Cluster analysis was used to better understand differences in the chemical composition of bryophyte samples and to evaluate possible usage of these methods in the chemotaxonomy of bryophytes.     

A study of the catalytic properties of the nitrile hydratase immobilized on aluminum oxides and carbon-containing adsorbents

The nitrile hydratase isolated from Rhodococcus ruber strain gt1, displaying a high nitrile hydratase activity, was immobilized on unmodified aluminum oxides and carbon-containing adsorbents, including the carbon support Sibunit. The activity and operational stability of the immobilized nitrile hydratase were studied in the reaction of acrylonitrile transformation into acrylamide. It was demonstrated that an increase in the carbon content in the support led to an increase in the amount of adsorbed enzyme and, concurrently, to a decrease in its activity. The nitrile hydratase immobilized on Sibunit and carbon-containing aluminum α-oxide having a “crust” structure displayed the highest operational stability in acrylonitrile hydration. It was shown that the thermostability of adsorbed nitrile hydratase increased by one order of magnitude.