Calculation of the relative metastabilities of proteins using the CHNOSZ software package

<p>Abstract</p> <p>Background</p> <p>Proteins of various compositions are required by organisms inhabiting different environments. The energetic demands for protein formation are a function of the compositions of proteins as well as geochemical variables including temperature, pressure, oxygen fugacity and pH. The purpose of this study was to explore the dependence of metastable equilibrium states of protein systems on changes in the geochemical variables.</p> <p>Results</p> <p>A software package called CHNOSZ implementing the revised Helgeson-Kirkham-Flowers (HKF) equations of state and group additivity for ionized unfolded aqueous proteins was developed. The program can be used to calculate standard molal Gibbs energies and other thermodynamic properties of reactions and to make chemical speciation and predominance diagrams that represent the metastable equilibrium distributions of proteins. The approach takes account of the chemical affinities of reactions in open systems characterized by the chemical potentials of basis species. The thermodynamic database included with the package permits application of the software to mineral and other inorganic systems as well as systems of proteins or other biomolecules.</p> <p>Conclusion</p> <p>Metastable equilibrium activity diagrams were generated for model cell-surface proteins from archaea and bacteria adapted to growth in environments that differ in temperature and chemical conditions. The predicted metastable equilibrium distributions of the proteins can be compared with the optimal growth temperatures of the organisms and with geochemical variables. The results suggest that a thermodynamic assessment of protein metastability may be useful for integrating bio- and geochemical observations.</p

Isolation of Extremely Thermophilic Sulfate Reducers: Evidence for a Novel Branch of Archaebacteria

Extremely thermophilic archaebacteria are known to be metabolizers of elemental sulfur and the methanogens. A novel group of extremely thermophilic archaebacteria is described, which consists of sulfate-respiring organisms that contain pure factor 420 and that have been isolated from marine hydrothermal systems in Italy. They possess a third type of archaebacterial RNA polymerase structure previously unknown, indicating an exceptional phylogenetic position. Most likely, this group represents a third major branch within the archaebacteria. The existence of sulfate reducers at extremely high temperatures could explain hydrogen sulfide formation in hot sulfate-containing environments, such as submarine hydrothermal systems and deep oil wells

Hyperthermophilic Archae- and Eubacteria occurring within Indonesian Hydrothermal Areas

From 85 samples taken during cruise 45B of the R/V SONNE within the Sunda Arc subduction zone and from solfatara fields in Java, thermophilic and hyperthermophilic archae- and eubacteria were isolated. The archaebacteria belong to the genera Methanobacterium, Methanolobus, Methanosarcina, Acidianus, Thermoproteus, Desulfurococcus, Thermoplasma and to two up to now unknown genera of hyperthermophilic marine heterotrophs and continental metal mobilizers. The eubacterial hyperthermophilic isolates are a new species of Thermotoga and a novel strictly anaerobe, thriving by H2/N03"-autotrophy

Stable carbon and nitrogen isotope ratios of Eucalyptus and Acacia species along a seasonal rainfall gradient in Western Australia

Stable carbon and nitrogen isotope ratios (delta13C and delta15N) in leaves of Eucalyptus and Acacia species were investigated together with specific leaf area (SLA), leaf nitrogen (N) and leaf phosphorous (P) concentration along a north-south transect through Western Australia covering winter- and summer-dominant rainfall between 100 and 1200 mm annually. We investigated 62 Eucalyptus and 78 woody Fabaceae species, mainly of the genus Acacia. Delta13C increased with latitude without distinct separation of rainfall regime (-29.5‰ + 1.3‰ at tropical latitude (15°S) and -25.7‰ + 1.1‰ at winter-rains (31°S)). Delta15N increased with southern latitudes (0.5‰ + 1.6‰ at 15°S; 5.8‰ + 3.3‰ at 24 to 29°S; 4.6‰ + 3.5‰ at 31°S). The variation in delta13C and delta15N was mainly due to speciation of Eucalyptus and Acacia into very local populations. There was not a single species that covered the range of conditions. The variation in leaf traits was larger between than within species. Nitrogen concentrations were 11.9 + 1.05 mg g-1 in Eucalyptus, but reached 18.7 + 4.1 mg g-1 in Acacia, even though delta15N gave no clear indication for N2-fixation. Comparing freshly burnt and un-burnt sites, delta15N values appear to be mainly determined by fire. In a multiple regression, latitude (as surrogate for seasonality), rainfall, leaf nitrogen concentration, specific leaf area and nitrogen fixation were significant and explained 69% of the variation of delta13C, but only 36% of the variation of delta15N. Higher nitrogen and phosphorus concentration could give Acacia an advantage over Eucalyptus in arid regions of undefined rainfall

Marri, Mallee, Mulga: Pflanzenvielfalt Westaustraliens

Western Australia is one of the „hot spots“ of global biodiversity with more than 10,000 plant species, a lot of them endemic to this region. Australia is associated in the minds of many people with eucalypts, including the genus Eucalyptus but also Corymbia, which was separated from Eucalyptus just a few years ago. Different vegetation types of Western Australia dominated by eucalypts are presented, also heathlands, Acacia shrublands and tropical dry forests and savannas from the Kimberley

Isolation, taxonomy and phylogeny of hyperthermophilic microorganisms

Hyperthermophilic Archaea and Bacteria with optimal growth temperatures between 80 and 110°C have been isolated from geo- and hydro-thermally heated terrestrial and submarine environments. 16S rRNA sequence comparisons indicate great phylogenetic diversity among the 23 different genera represented. Hyperthermophiles consist of anaerobic and aerobic chemolithoautotrophs and heterotrophs growing at neutral or acidic pH. Their outstanding heat resistance makes them as interesting objects for basic research as for biotechnology in the future

The first successful crystallization of a prokaryotic extremely thermophilic outer surface layer glycoprotein

Methanothermus fervidus belongs to the group of hyperthermophilic Archaea. The Archaea comprise organisms that live under environmental extremes. like high temperature, low pH value or high salt concentration. The outer surface of the pseudomurein sacculi of the cells of Methanothermus fervidus is covered by glycoprotein subunits (S-Iayer) directly exposed to the extreme environment. The elucidation of the crystal structure of this surface glycoprotein may provide important information on the survival strategies of these unusual micro-organisms. Before our investigations neither three-dimensional crystals have been obtained nor X-ray analyses were performed. Only electron microscopic and computer image enhancement techniques have been applied to obtain structural information from crystalline two-dimensional S-layer sheets. We describe here the successful crystallization of this surface glycoprotein under microgravity conditions