Overexpression of the RNA polymerase alpha subunit reduces transcription of Bvg-activated virulence genes in Bordetella pertussis.

Overexpression of the RNA polymerase alpha subunit in Bordetella pertussis reduces expression of the virulence factor pertussis toxin. Here we show that this reduction is at the level of transcription, is reversed by overexpression of the transcriptional activator BvgA, and is dependent on the C-terminal domain of alpha.

Heterologous expression in the Archaea: transcription from Pyrococcus furiosus gdh and mlrA promoters in Haloferax volcanii.

Multicopy plasmids containing the promoter regions for gdh and mlrA genes from Pyrococcus furiosus were propagated in Haloferax volcanii. High-level expression was detected from gdh promoter sequences, with transcription initiating at the same start-site as that found in P. furiosus. For mlrA, several transcripts were detected, with one initiating at the P. furiosus start-site; removal or disruption of the likely P. furiosus boxA element resulted in the disappearance of this transcript, indicating that these sequences were utilized by the H. volcanii RNA polymerase for initiation. This is the first demonstration of the utilization of promoters from a hyperthermophilic archaeon in a mesophilic haloarchaeon and provides further evidence for the unity of transcription processes in the domain Archaea.

The vaccinia virus E3L gene product interacts with both the regulatory and the substrate binding regions of PKR: implications for PKR autoregulation.

The vaccinia virus E3L gene product, pE3, is a dsRNA binding protein that prevents activation of the interferon-induced, dsRNA-activated protein kinase, PKR. Activation of PKR, which results in phosphorylation of the translation initiation factor, eIF2alpha, leads to the inhibition of protein synthesis, a process involved in defense against virus infection. The E3L gene product has a conserved dsRNA binding domain (DRBD) in its carboxyl-terminal region and has been shown to function in vitro by sequestration of dsRNA. We have utilized in vitro binding assays and the yeast two-hybrid system to demonstrate direct interactions of pE3 with PKR. By these methods, we demonstrate that pE3 interacts with two distinct regions in PKR, the amino-terminal (amino acids 1-99) located in the regulatory domain and the carboxyl-terminal (amino acids 367-523) located in the catalytic domain. The amino-terminal region of PKR that interacts with pE3 contains a conserved DRBD, suggesting that PKR can form nonfunctional heterodimers with pE3, analogous to those seen with other dsRNA binding proteins. Interaction of pE3 with the amino-terminal region of PKR is enhanced by dsRNA. In contrast, dsRNA reduces the interaction of pE3 with the carboxyl-terminal region of PKR. Competition experiments demonstrate that the carboxyl-terminal region of PKR, to which pE3 binds, overlaps the region with which eIF2alpha and the pseudosubstrate pK3 interact, suggesting that pE3 may also prevent PKR activation by masking the substrate binding domain. Like pE3, the amino-terminal region of PKR also interacts with the carboxyl-terminal domain of PKR. These interactions increase our understanding of the mechanisms by which pE3 downregulates PKR. In addition, the PKR-PKR interactions observed leads us to suggest a novel autoregulatory mechanism for activation of PKR in which dsRNA binding to the DRBD(s) induces a conformational change that results in release of the amino terminal region from the substrate binding domain, allowing access to eIF2alpha and its subsequent phosphorylation.

[The structure of the morbidity with temporary loss of work capacity among female workers in the cotton industry]. / Struktura zabolevaemosti s vremennoi utratoi trudosposobnosti rabotnits khlopchatobumazhnogo proizvodstva.

A comparative study of the levels of temporary loss of working capacity among females working in the cotton production industry in different working and social conditions allowed to reveal higher incidence of morbidity in this category of workers as compared with the control group and to work out a complex of measures aimed at reducing this morbidity and ensuring stable recovery.

[Physico-chemical properties of DNA from representatives of a population of Pseudomonas bacteriophages]. / Fiziko-khimicheskie svoistva DNK predstavitelei populiatsii bakteriofagov psevdomonad.

Twenty-four bacteriophages of Pseudomonas similar in terms of their morphology and structure were studied. The genomes of 23 bacteriophages from a population widespread in Belorussia and of one bacteriophage from the Krasnodar Region were shown to be double-helical DNAs with the content of GC base pairs from 46.8 to 66.7%. Four endonucleases (Eco R1, Hind III, Bam H1, and Eco RV) were used in the restriction analysis. Phage 8 which differed from the other phages in the area of its distribution was found to represent an individual group. The other phages were subdivided into eight related groups and had an identical restriction map within each group. The mean molecular masses of phage DNAs calculated by the method of summing the molecular masses of restricts ranged from 27.8 to 31.0 MDa.

[Lytic activity of Pseudomonas bacteriophages]. / Liticheskaia aktivnost' bakteriofagov psevdomonad.

None of the 24 Pseudomonas syringae bacteriophages were found to be identical in the spectrum of lytic action. The phages were subdivided into five groups according to the number of sensitive bacterial strains and their qualitative composition.

[Heterogeneity of a Pseudomonas bacteriophage population]. / Geterogennost' populiatsii bakteriofagov Psevdomonad.

Twenty-five isolates of virulent bacteriophages for Pseudomonas belonging to the morphological group C (Bradley, 1967) were obtained from different natural habitats. The phages of each isolate were found to differ from one another in at least one of the following characteristics: the sensitivity to an osmotic shock, to heating at 60 degrees C and to UV; the ability to cause lysis of 86 Pseudomonas strains; the reaction of neutralisation with antisera. At the same time, the phages were related by the existence of common antigens. These properties are responsible for the genetic stability of the bacteriophages in their complicated relationship with their host, Pseudomonas bacteria.