Research Projects

Rare Earth Elements (REEs) are a group of seventeen elements in the periodic table that play an integral role in making various components of electronics and renewable energy devices, as well as medical and defense equipment. However, for these elements to be used in the said applications, they must be isolated first in their pure form, which is extremely difficult to achieve due to their nearly identical physical and chemical properties. Liquid-liquid extraction (LLE), one of the commonly used separation methods in hydrometallurgy, can separate REEs from other metal contaminants and, to some extent, one REE from another. However, LLE is an energy and cost-intensive process, requires multiple separation stages to achieve desirable purities, and generates significant quantities of hazardous chemical waste. Protein-based REE separation can be an attractive alternative in this regard, especially given a protein's potential for high selectivity for certain chemistries, mild process conditions, and low environmental impacts. Prior biochemical studies demonstrated that lanmodulin, a methylotropic bacterial protein, immobilized on porous beads can effectively separate REEs from non-REE metal pollutants as well as differentiate heavy and light REE fractions under flow through conditions (Cotruvo Junior, JA., et al., J. Am. Chem. Soc., 2018; Dong, Z., et al., ACS Cent. Sci., 2021). While these protein-based REE separation techniques have yielded impressive results, intra-REE separation, particularly intra-light and intra-heavy REE separations, has yet to be realized. Designing biotechnologies capable of efficient intra-REE separation through protein engineering requires fundamental understanding of lanmodulin functionality, particularly with respect to the protein dynamics and the nature of protein interactions with REEs and non-REEs, which are still poorly understood at the molecular-level. Accordingly, we will employ computer-aided mathematical modeling, atomistic molecular dynamics simulation, and machine learning in conjunction with several experimental approaches to reveal the underlying mechanisms responsible for lanmodulin's selective REE recognition, binding, binding-induced conformational change, and cooperativity. Here, we hypothesize that there are subtle differences at the molecular level among REEs in terms of the order in which they bind to lanmodulin's four metal binding sites, as well as the degree of cooperation lanmodulin exhibits during various stages of REE binding. We believe these differentiating factors can be leveraged to design a highly selective variant of lanmodulin for the recovery of a specific REE. To examine the hypothesis, we will undertake the following research objectives: (1) to elucidate the molecular mechanism behind the cooperative binding and binding-induced conformational change of lanmodulin in the presence of various light and heavy REEs, (2) to assess the impact of amino acid substitutions In Silico on lanmodulin’s ability to selectively bind to a specific REE, and finally (3) to design a highly potent engineered lanmodulin library tailored towards recovery of specific REE(s). Overall, our proposed work will provide a deep understanding of the molecular hallmarks underlying lanmodulin's preferential selectivity for different REEs that will further aid to achieve intra-light and intra-heavy REE separation via protein engineering. Moreover, this work will enhance our understanding of a broader array of metal-sensing proteins beyond lanmodulin, such as calmodulin, transferrin, ferritin, and others.