Eman A. Alasadi, Wonseok Choi, Xiaobing Chen, Joseph A. Cotruvo Jr* and Carlos R. Baiz*,
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引用次数: 0
Abstract
Lanmodulins are small, ∼110-residue proteins with four EF-hand motifs that demonstrate a picomolar affinity for lanthanide ions, making them efficient in the recovery and separation of these technologically important metals. In this study, we examine the thermodynamic and structural complexities of lanthanide ion binding to a 41-residue domain, EF 2–3, that constitutes the two highest-affinity metal-binding sites in the lanmodulin protein from Methylorubrum extorquens. Using a combination of circular dichroism (CD) spectroscopy, isothermal titration calorimetry (ITC), two-dimensional infrared (2D IR) spectroscopy, and molecular dynamics (MD) simulations, we characterize the metal binding capabilities of EF 2–3. ITC demonstrates that binding occurs between peptide and lanthanides with conditional dissociation constants (Kd) in the range 20–30 μM, with no significant differences in the Kd values for La3+, Eu3+, and Tb3+ at pH 7.4. In addition, CD spectroscopy suggests that only one binding site of EF 2–3 undergoes a significant conformational change in the presence of lanthanides. 2D IR spectroscopy demonstrates the presence of both mono- and bidentate binding configurations in EF 2–3 with all three lanthanides. MD simulations, supported by Eu3+ luminescence measurements, explore these results, suggesting a competition between water–lanthanide and carboxylate–lanthanide interactions in the EF 2–3 domain. These results underscore the role of the core helical bundle of the protein architecture in influencing binding affinities and communication between the metal-binding sites in the full-length protein.
期刊介绍:
ACS Chemical Biology provides an international forum for the rapid communication of research that broadly embraces the interface between chemistry and biology.
The journal also serves as a forum to facilitate the communication between biologists and chemists that will translate into new research opportunities and discoveries. Results will be published in which molecular reasoning has been used to probe questions through in vitro investigations, cell biological methods, or organismic studies.
We welcome mechanistic studies on proteins, nucleic acids, sugars, lipids, and nonbiological polymers. The journal serves a large scientific community, exploring cellular function from both chemical and biological perspectives. It is understood that submitted work is based upon original results and has not been published previously.