2010 Annual Science Report

Montana State University Reporting  |  SEP 2009 – AUG 2010

Executive Summary

Iron-sulfur clusters are ubiquitous in biology and possess features that are reminiscent of the features of iron-sulfur minerals. The structure/reactivity relationships between iron-sulfur metalloenzymes and iron-sulfur minerals has been noted by a number of investigators and is the basis for aspects of a “Metabolism First” origin of life scenario and more specifically for the “Iron Sulfur World”. These provide a framework for the research being conducted at the Astrobiology Biogeocatalysis Research Center with a focus on revealing the connection between iron-sulfur minerals and iron-sulfur metalloenzymes. The adaptation of iron-sulfur motifs from the abiotic world to the biological world may have been an early event in the generation of the building blocks of life on Earth and possibly a common feature of life elsewhere in the universe. ABRC research is aimed at providing the structural and chemical determinants that define the catalytic properties of iron-sulfur-based ... Continue reading.

Field Sites
9 Institutions
15 Project Reports
38 Publications
10 Field Sites

Project Reports

  • Minerals to Enzymes: The Path to CO Dehydrogenase/Acetyl – CoA Synthase

    The relationship between structure and reactivity of iron-sulfur minerals and the active sites of iron-sulfur enzymes is too strong to be coincidental. We and others have proposed that the emergence and genesis of iron-sulfur cluster enzymes occurred by a stepwise process in which mineral motifs were first nested in simple organic polymers and then in response to selective pressure evolved specific gene encoded protein nest that confer high specific enzyme activities. We are examining this hypothesis through nesting NiFeS motifs in a variety of organic nest and examining the structural determinants of reactivity.

    ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 7.1 7.2
  • Radical SAM Enzyme Functional Diversity and Evolution

    The role of radical generating iron-sulfur enzymes in making modification to iron-sulfur motifs in biology are key to the maturation of nitrogen fixing and hydrogen oxidizing enyzme activities. These enzymes act through a mechanism analogous to what has been termed ligand assisted catalysis in discussions of tuning the reactivity of iron sulfur mineral motifs before the advent of life. This strong parallel between biological and abiotic processes provides a basis to better understand the transition from prebiotic chemistry to biochemistry or the transition from the nonliving to the living EArth.

    ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4
  • The ABRC Philosophy of Astrobiology and the Origin of Life Discussion Group

    At Montana State University we have developed a think tank that involves Philsophers and Scientists and different points in their careers (Professor, Graduate Students, and Undergraduate Students) for the discussion of aspects of Origin of Life Theories. The think tank team has tackled a number of interesting problems and has presented there findings at national and international meetings and published their findings in the journal “Origin of Life and Evolution or Biospheres”.

    ROADMAP OBJECTIVES: 3.1 3.2
  • Viral Ecology and Evolution

    We are interested in studying the viruses inhabiting the acidic hot springs within Yellowstone. We hypothesize that further understanding the viral dynamics, diversity, and composition will aid in the understanding of early Earth and how cellular life may have evolved.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2
  • Structure, Reactivity, and Biosynthesis of Cataylic Iron-Sulfur Clusters

    We are examining the biosynthesis of complex iron-sulfur cluster to determine the specific chemistry associated with modifying iron-sulfur motifs in biology for different functions. We then relate the chemistry associated with these modifying reactions to reactions that could potentially modify iron-sulfur mineral motifs in the early non-living Earth to promote analogous reactivity.

    ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 4.1 7.1 7.2
  • Molecular Paleontology of Iron-Sulfur Enzymes

    In this project we are attempting to trace back in the evolutionary record using specific genetic events as markers. We are using specific gene fusion and gene duplication events in the genetic record to place a chronological sequence to the advent of nitrogen fixation, certain modes of hydrogen metabolism, and both anoxygenic and oxygenic photosynthesis.

    ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 4.1 5.1 5.2 5.3 6.1
  • Subglacial Methanogenesis and Implications for Planetary Carbon Cycling

    Methanogens are thought to be among the earliest emerging life forms. Today, the distribution of methanogens is narrowly constrained, due in part to the energetics of the reactions which support this functional class of organism (namely carbon dioxide reduction with hydrogen and acetate fermentation). Methanogens utilize a number of metalloenzymes that have active site clusters comprised of a unique array of metals. The goals of this project are 1) identifying a suite of biomarkers indicative of biological CH4 production 2). quantifying the flux of CH~4~ from sub-ice systems and 3). developing an understanding how life thrives at the thermodynamic limits of life. This project represents a unique extension of the ABRC and bridges the research goals of several nodes, namely the JPL-Icy Worlds team and the ASU-Follow the Elements team.

    ROADMAP OBJECTIVES: 2.1 5.1 5.2 5.3 7.1 7.2
  • X-Ray Characterization of Modified Fe-S Mineral Surfaces

    High energy X-ray radiations generated by tunable synchrotron lightsources were used to characterize both the location of the electrons and the atomic centers in modified Fe-S minerals and particles. We have exploited the complementary information content of three different detections techniques in both soft and hard X-ray energy range. We confirmed the formation of a reduced pyrite structure from hydrogen atom exposure experiments. The formation of a reduced pyrite surface is relevant to small molecule activation processes of abiotic molecules toward formation of more complex molecules, such as amino and nucleic acids.

    ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2
  • Virtual Catalysis From Molecular Beam Scattering

    Molecular beam/surface scattering experiments provide a controlled environment for modeling abiotic processes at the interface of lytho- and atmosphere. Specifically, it has been proposed that exposed rock surfaces may have played a role in modifying activated atmospheric molecules in the presence of UV radiation toward the building blocks of life. We have found that extended exposure of pyrite mineral surfaces to hydrogen atoms creates a reduced iron surface. The reduced state and the modified geometric structure of the surface iron atoms were confirmed by X-ray spectroscopy. Furthermore, this modified pyrite surface shows remarkable chemical reactivity in converting the hyperthermal beam of N2 to ammonia.

    ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2
  • Biomineralization

    Minerals formed by biological systems such as bones, teeth, and seashells can be used to identify the organism from which they came. Thus these mineral structures are unique biosignatures. Our efforts are focused on trying to identify the key underlying factors that are responsible for the subtle differences in the structure of these biominerals imparted by the organic biological components of the organism. We therefore study the interface between the mineral and the organic components with a particular focus on very early events in the mineral growth process.

    ROADMAP OBJECTIVES: 7.1 7.2
  • Complex Chemical Networks in Astrobiology

    Many of the building blocks for prebiotic chemistry form in dark molecular clouds — dense regions of interstellar gas and dust from which stars and planetary systems are also born. Sophisticated chemical models have been developed to understand the complex network of reactions that can convert simple precursor molecules to the complex organics that are often found in meteorites and comets. We have begun to apply the tools of network theory — a branch of mathematics that studies interconnected complex systems from cellular metabolism to Facebook — to gain more insight into the structure of these interstellar chemical networks. This approach allows us to make comparisons between complex chemical networks in biology, astronomy, and planetary science, searching for unifying general principles and critical differences between living and non-living systems.

    ROADMAP OBJECTIVES: 3.1 3.2
  • Functional Based Habitability – Defining the Environmental Factors That Constrain Modes of Microbial Metabolism

    To set the stage for space exploration and the search for life in the universe, it is necessary to establish the boundaries that define habiltability on Earth. Previous studies have emphasized using simple binary parameters to establish where life occurs and where life does not occur on Earth. We are attempting to take this to another level and establish through mutlivariable statistics the parameters that not only constrain the life but what parameters constrain the set of metabolic processes that sustain life as a function of environment.

    ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 6.2
  • PHL 278: A Gateway Course for a Minor in Astrobiology

    We have recently developed obtained Montana Board of Regents for an undergraduate minor in Astrobiology at Montana State University. The Minor includes courses in Earth Sciences, Physics, Astronomy, Microbiology, Ecology, Chemistry, and Philosophy. Two new courses have been developed as part of the minor, one of which is a gateway or introductory course examines the defining characteristics of life on earth as well as the challenges of a science that studies life and its origin. The other course which will be offered fall 2011 is the capstone course for the minor which will delved into the science of Astrobiology in more detail and targeted for Juniors and Seniors that have fulfilled the majority of the requisite course requirements for the curriculum.

    ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 3.3 3.4 4.1 4.2 4.3 5.1 5.2 5.3 6.1 6.2 7.1 7.2
  • Rationalized Chemical Surface Modifications

    Using biological examples such as nitrogen fixation by nitrogenase, hydrogen evolution and uptake by hydrogenases, and reversible CO/CO2 conversion by CO dehydrogenase, we began to study the effect of heterometal (Mo, V, Ni) substitution in iron-sulfur minerals and particles. We have successfully bound molybdenum sulfide on pyrite mineral surfaces and exploring the synthetic feasibility of doping Ni into freshly precipitated FeS particles. Preliminary reactivity studies indicated higher yields in formation of ammonia from nitrogen oxides at hydrothermal conditions relative to the pure iron-sulfur systems.

    ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2
  • Surface Chemistry on Iron-Sulfur Minerals

    Progress has been made in defining competitive abiotic pathways for reducing nitrogen compounds to ammonia from nitrogen oxides relative to the dinitrogen. Using pyrite mineral surfaces and freshly precipitated Fe-S particles, we showed that under hydrothermal conditions nitrite (NO2-), nitrate (NO3-), as well as nitric oxide (NO) can be converted to ammonia to comparable yields than starting from dinitrogen (N2). Formation of ammonia or ammonium ion in aqueous solution is considered as an essential step toward creating amino acids that are key building blocks of life.

    ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2