2011 Annual Science Report
Montana State University Reporting | SEP 2010 – AUG 2011
Minerals to Enzymes: The Path to CO Dehydrogenase/Acetyl – CoA Synthase
We have through NAI Director’s discretionary initiated a project to probing the structural determinants for nickel-iron-sulfur based reversible carbon monoxide oxidation. We are probing whether we can mimic the reactivity of carbon monoxide dehydrogenase to some extent by simple organic nesting and synthesis of nickel-iron-sulfur clusters using a model system we have developed.
The major emphasis of the research in the ABRC is relating the structure and reactivity of iron-sulfur minerals and iron-sulfur enzymes to better understand the origin of biological processes. Specifically we are using iron-sulfur motifs as a model system to understand the transition between the abiotic early Earth and biology. We have been able to provide growing support for our overarching hypothesis that there is a distinct connection between iron-sulfur minerals and iron-sulfur enzymes worthy of this line of inquiry in work on the complex iron sulfur containing nitrogenases (nitrogen fixation) and hydrogenases (hydrogen metabolism). The enzymes responsible for reversible carbon dioxide oxidation (carbon monoxide dehydrogenases) are also complex iron-sulfur enzymes. In this project we are testing the hypothesis that the path from minerals to enzymes occur through the organic nesting of clusters and that the evolutionary ancestors of modern iron sulfur enzymes were simply peptides or polypeptides capable of binding metal clusters. In this work we have used a model enzyme which we have structurally characterized and found to have an open cavity with metal binding ligands and the capacity to bind metal clusters. When we incubate this protein with the various concentrations of nickel, iron, and sulfur we are able to generate different metal clusters some of which have detectable levels of carbon monoxide oxidation catalytic activity. We are in the process now of designing minimal cluster forming peptide motifs to indentify the minimum structural determinants of catalysis.
PROJECT INVESTIGATORS:John Peters
PROJECT MEMBERS:Robert Szilagyi
Guana Siluvai Pitchai
RELATED OBJECTIVES:Objective 3.1
Sources of prebiotic materials and catalysts
Origins and evolution of functional biomolecules
Origins of energy transduction
Origins of cellularity and protobiological systems
Biosignatures to be sought in Solar System materials
Biosignatures to be sought in nearby planetary systems