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The ultrahigh-affinity transport protein repertoire of SAR11 marine bacteria

Marine microbes constitute the majority of ocean biomass and have a global impact on the Earth’s ecosystems, chemistry, and climate. Our understanding of marine microbial processes has been dramatically advanced by recent advances in next-generation sequencing of microbial DNA and RNA in environmental samples, allowing us to infer the spatial and temporal distribution of various biochemical processes throughout the ocean. However, a limitation of these analyses is that they rely on predictions of protein function that are often inaccurate. In this talk, I will describe how experimental annotation of protein function can provide insight into the physiology, metabolism, and biogeochemical impact of marine microbes, focusing on our recent work on transport proteins in SAR11 bacteria. SAR11 bacteria are among the most abundant microbes on Earth and rely heavily on transport proteins that facilitate uptake of specific compounds to thrive under nutrient-poor conditions in the surface ocean. Biochemical, structural, and biophysical analysis of transport proteins allowed us to investigate the global contribution of SAR11 bacteria to uptake of dissolved organic matter in the ocean and identify new adaptations of SAR11 bacteria at the molecular level that contribute to their remarkable evolutionary success in nutrient-poor environments. I will also briefly discuss how this approach might be extended to identify chemical signals that control ecologically significant bacteria-microalgae interactions.

Biography

Ben is a protein biochemist with research interests spanning structural biology, evolutionary biochemistry, biotechnology, and marine microbiology. He completed his PhD in the Research School of Chemistry at the Australian National University in 2017. After working as a Research Officer and then Head of Protein Biochemistry at Myrio Therapeutics, he was awarded a JSPS Postdoctoral Fellowship and joined the Protein Engineering and Evolution Unit at the Okinawa Institute of Science and Technology in 2020. He started an independent position in the School of Molecular Sciences at the University of Western Australia in January 2025 to study the biogeochemical impacts and biotechnological applications of enzymes from the marine microbiome.