Full Repression of RNA Polymerase III Transcription Requires Interaction between Two Domains of Its Negative Regulator Maf1

Maf1, first identified in yeast Saccharomyces cerevisiae, is a general negative regulator of RNA polymerase III (Pol III). Transcription regulation by Maf1 is important under stress conditions and during the switch between fermentation and respiration. Maf1 is composed of two domains conserved during evolution. We report here that these two domains of human Maf1 are resistant to mild proteolysis and interact together as shown by pull-down and size-exclusion chromatography and that the comparable domains of yeast Maf1 interact in a two-hybrid assay. Additionally, in yeast, a mutation in the N-terminal domain is compensated by mutations in the C-terminal domain. Integrity of both domains and their direct interaction are necessary for Maf1 dephosphorylation and subsequent inhibition of Pol III transcription on a nonfermentable carbon source. These data relate Pol III transcription inhibition to Maf1 structural changes

Novel layers of RNA polymerase III control affecting tRNA gene transcription in eukaryotes

RNA polymerase III (Pol III) transcribes a limited set of short genes in eukaryotes producing abundant small RNAs, mostly tRNA. The originally defined yeast Pol III transcriptome appears to be expanding owing to the application of new methods. Also, several factors required for assembly and nuclear import of Pol III complex have been identified recently. Models of Pol III based on cryo-electron microscopy reconstructions of distinct Pol III conformations reveal unique features distinguishing Pol III from other polymerases. Novel concepts concerning Pol III functioning involve recruitment of general Pol III-specific transcription factors and distinctive mechanisms of transcription initiation, elongation and termination. Despite the short length of Pol III transcription units, mapping of transcriptionally active Pol III with nucleotide resolution has revealed strikingly uneven polymerase distribution along all genes. This may be related, at least in part, to the transcription factors bound at the internal promoter regions. Pol III uses also a specific negative regulator, Maf1, which binds to polymerase under stress conditions; however, a subset of Pol III genes is not controlled by Maf1. Among other RNA polymerases, Pol III machinery represents unique features related to a short transcript length and high transcription efficiency

Hot nuclear matter with dilatons

We study hot nuclear matter in a model based on nucleon interactions deriving from the exchange of scalar and vector mesons. The main new feature of our work is the treatment of the scale breaking of quantum chromodynamics through the introduction of a dilaton field. Although the dilaton effects are quite small quantitatively, they affect the high-temperature phase transition appreciably. We find that inclusion of the dilaton leads to a metastable high-density state at zero pressure, similar to that found by Glendenning who considered instead the admixture of higher baryon resonances.Comment: 10 pages, LaTeX with equation.sty (optional) and epsfig.sty, 11 figures packed with uufiles. Final, published version (small changes from original preprint

Comparative analysis of the availability of cinema websites, taking into account the principles of universal design

The subject of this study is to conduct a comparative analysis of cinema websites, taking into account the principles of universal design. The universal designing is a philosophy which central assumption is to create products, including graphic interfaces so that they are accessible to as many users as possible. An accessibility is a term that describes the extent to which users of different ages, with varying degrees of physical or mental fitness, can use it. Therefore, it is essential to adapt the interface to the largest possible audience when designing the interface. In the paper the following hypothesis has been defined: "The application of universal design principles increases the accessibility of websites”. The "Multikino" website has been selected for the research, which does not require the universal design, and the website created for the purpose of this study that meets these requirements. The research methods used in the study include eye-tracking, checking compliance with WCAG (ang. Web Content Accessibility Guidelines) guidelines using the WAVE (ang. Web Accessibility Evaluation Tool) tool, and conducting an interface assessment survey

Specific features of RNA polymerases I and III:Structure and assembly

RNA polymerase I (RNAPI) and RNAPIII are multi-heterogenic protein complexes that specialize in the transcription of highly abundant non-coding RNAs, such as ribosomal RNA (rRNA) and transfer RNA (tRNA). In terms of subunit number and structure, RNAPI and RNAPIII are more complex than RNAPII that synthesizes thousands of different mRNAs. Specific subunits of the yeast RNAPI and RNAPIII form associated subcomplexes that are related to parts of the RNAPII initiation factors. Prior to their delivery to the nucleus where they function, RNAP complexes are assembled at least partially in the cytoplasm. Yeast RNAPI and RNAPIII share heterodimer Rpc40-Rpc19, a functional equivalent to the αα homodimer which initiates assembly of prokaryotic RNAP. In the process of yeast RNAPI and RNAPIII biogenesis, Rpc40 and Rpc19 form the assembly platform together with two small, bona fide eukaryotic subunits, Rpb10 and Rpb12. We propose that this assembly platform is co-translationally seeded while the Rpb10 subunit is synthesized by cytoplasmic ribosome machinery. The translation of Rpb10 is stimulated by Rbs1 protein, which binds to the 3′-untranslated region of RPB10 mRNA and hypothetically brings together Rpc19 and Rpc40 subunits to form the αα-like heterodimer. We suggest that such a co-translational mechanism is involved in the assembly of RNAPI and RNAPIII complexes

Axially Symmetric Multisphalerons in Yang-Mills-Dilaton Theory

We construct sequences of axially symmetric multisphaleron solutions in SU(2) Yang-Mills-dilaton theory. The sequences are labelled by a winding number $n>1$. For $n=1$ the known sequence of spherically symmetric sphaleron solutions is obtained. The solutions within each sequence are labelled by the number of nodes $k$ of the gauge field functions. The limiting solutions of the sequences correspond to abelian magnetic monopoles with $n$ units of charge and energy $E \propto n$.Comment: 18 pages, including 7 postscript figure

Effects of Meson Mass Reduction on the Properties of Neutron Star Matter

We investigate the effects of meson-mass reduction on the properties of the neutron star matter. We adopt the Brown-Rho scaling law to take into account density dependence of meson masses in the quantum hadrodynamics, quark-meson coupling and modified quark-meson coupling models. It is found that the equation of state becomes stiff when the mass of meson is reduced in dense medium. We discuss its implication on the properties of the neutron star.Comment: 3 pages, 2 figures and 10 references. Use espcrc1.sty. Appeared in the proceedings of the 7th international symposium on Nuclei in the Cosmos, Fuji-Yoshida, Japan, July 8-12, 200

Analysis of Chiral Mean-Field Models for Nuclei

An analysis of nuclear properties based on a relativistic energy functional containing Dirac nucleons and classical scalar and vector meson fields is discussed. Density functional theory implies that this energy functional can include many-body effects that go beyond the simple Hartree approximation. Using basic ideas from effective field theory, a systematic truncation scheme is developed for the energy functional, which is based on an expansion in powers of the meson fields and their gradients. Chiral models are analyzed by considering specific lagrangians that realize the spontaneously broken chiral symmetry of QCD in different ways and by studying them at the Hartree level. Models that include a light scalar meson playing a dual role as the chiral partner of the pion and the mediator of the intermediate-range nucleon-nucleon interaction, and which include a "Mexican-hat" potential, fail to reproduce basic ground-state properties of nuclei. In contrast, chiral models with a nonlinear realization of the symmetry are shown to contain the full flexibility inherent in the general energy functional and can therefore successfully describe nuclei.Comment: 47 pages, REVTeX 3.0 with epsf.sty, plus 12 figures in separate uuencoded compressed postscript fil