Download MendeleyMolecular basis for inhibition of methane clathrate growth by a deep subsurface bacterial protein.
Huard, D.J.E., Johnson, A.M., Fan, Z., Kenney, L.G., Xu, M., Drori, R., Gumbart, J.C., Dai, S., Lieberman, R.L., Glass, J.B.(2023) PNAS Nexus 2: pgad268-pgad268
- PubMed: 37644917 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1093/pnasnexus/pgad268
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8DOT - PubMed Abstract:
Methane clathrates on continental margins contain the largest stores of hydrocarbons on Earth, yet the role of biomolecules in clathrate formation and stability remains almost completely unknown. Here, we report new methane clathrate-binding proteins (CbpAs) of bacterial origin discovered in metagenomes from gas clathrate-bearing ocean sediments. CbpAs show similar suppression of methane clathrate growth as the commercial gas clathrate inhibitor polyvinylpyrrolidone and inhibit clathrate growth at lower concentrations than antifreeze proteins (AFPs) previously tested. Unlike AFPs, CbpAs are selective for clathrate over ice. CbpA 3 adopts a nonglobular, extended structure with an exposed hydrophobic surface, and, unexpectedly, its TxxxAxxxAxx motif common to AFPs is buried and not involved in clathrate binding. Instead, simulations and mutagenesis suggest a bipartite interaction of CbpAs with methane clathrate, with the pyrrolidine ring of a highly conserved proline residue mediating binding by filling empty clathrate cages. The discovery that CbpAs exert such potent control on methane clathrate properties implies that biomolecules from native sediment bacteria may be important for clathrate stability and habitability.
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive NW, Atlanta, GA 30332, USA.
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