Microbial Protein Structure Altered when Exposed to Soil Mineral Surfaces
New findings may improve predictions using decomposition models and shed light on potential changes in protein activity.
The degradation of soil organic matter by microbes plays an important role in atmospheric carbon levels. A recent study examined how soil minerals could affect the stability of microbial proteins, potentially influencing the rate of carbon dioxide release into the atmosphere.
The study shows that interactions with the surface of birnessite, but not other common soil minerals, have the potential to substantially alter the structure of bacterial proteins. These findings shed new light on how protein-mineral interactions could affect degradation rates of soil organic matter.
Soil contains the largest amount of terrestrial carbon on the planet, so a small change in soil carbon can have a large impact on atmospheric carbon dioxide levels. Therefore, understanding how organic carbon is released from soil into the atmosphere is a key question in climate science. Microbes produce enzymes that interact with soil minerals, and these protein-mineral interactions play an important role in the decomposition of soil organic carbon, which is subsequently released into the atmosphere. Not clear, however, is how different soil minerals affect the structure and function of microbial enzymes. To address this question, a team of researchers from the Department of Energy’s (DOE) Environmental Molecular Sciences Laboratory (EMSL), Oregon State University, and Leibniz Zentrum für Agrarlandschaftsforschung conducted molecular dynamics simulations to determine how interactions with surfaces of five common soil minerals affect the structure of a small bacterial protein called Gb1. The team performed simulations using the Cascade high-performance computer at EMSL, a DOE Office of Science user facility. The researchers found the Gb1 structure becomes highly altered due to interactions with Na+-birnessite mineral surfaces, but not kaolinite, montmorillonite, and goethite mineral surfaces. Interactions with birnessite caused the Gb1 protein structure to flatten and partially unravel. These findings shed light on how different soil minerals could affect the stability of microbial enzymes, thereby influencing the degradation rate of soil organic carbon. These insights build on previous, published experimental observations and could lead to more accurate projections of how much carbon dioxide could be released into the atmosphere as a result of microbial decomposition of soil organic matter.
Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory
This work was supported by the Department of Energy (DOE), Office of Science, Office of Biological and Environmental Research, including support of the Environmental Molecular Sciences Laboratory (EMSL), a DOE Office of Science user facility; and the “Understanding Molecular-Scale Complexity and Interactions of Soil Organic Matter” Intramural Project at EMSL.
Andersen, A., P. N. Reardon, S. S. Chacon, N. P. Qafoku, N. M. Washton, and M. Kleber. 2016. “Protein-Mineral Interactions: Molecular Dynamics Simulations Capture Importance of Variations in Mineral Surface Composition and Structure,” Langmuir 32(24), 6194-209. DOI: 10.1021/acs.langmuir.6b01198.