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Abstract Protein dynamics is at the heart of all cellular processes. Here, we utilize the dHis‐CuIINTA label to obtain site‐specific information on dynamics for both an α‐helix and β‐sheet site of GB1, the immunoglobulin binding domain of protein G. Spectral features found in our CW‐EPR measurements were consistent with the overall rigid nature of GB1 and with predictions from molecular dynamics simulations. Using this information, we show the potential of this approach to elucidate the role of dynamics in substrate binding of a functionally necessary α‐helix in human glutathione transferase A1‐1 (hGSTA1‐1). We observe two dynamical modes for the helix. The addition of the inhibitor GS‐Met and GS‐Hex resulted in hGSTA1‐1 to favor the more rigid active state conformation, while the faster mode potentially aids the search for substrates. Together the results illustrate the remarkable potential of the dHis‐based labelling approach to measure site‐specific dynamics using room temperature lineshape analysis.
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Beyond structure: Deciphering site‐specific dynamics in proteins from double histidine‐based EPR measurements
Abstract Site‐specific dynamics in proteins are at the heart of protein function. While electron paramagnetic resonance (EPR) has potential to measure dynamics in large protein complexes, the reliance on flexible nitroxide labels is limitating especially for the accurate measurement of site‐specific β‐sheet dynamics. Here, we employed EPR spectroscopy to measure site‐specific dynamics across the surface of a protein, GB1. Through the use of the double Histidine (dHis) motif, which enables labeling with a Cu(II) – nitrilotriacetic acid (NTA) complex, dynamics information was obtained for both α‐helical and β‐sheet sites. Spectral simulations of the resulting CW‐EPR report unique site‐specific fluctuations across the surface of GB1. Additionally, we performed molecular dynamics (MD) simulations to complement the EPR data. The dynamics observed from MD agree with the EPR results. Furthermore, we observe small changes ingǁvalues for different sites, which may be due to small differences in coordination geometry and/or local electrostatics of the site. Taken together, this work expands the utility of Cu(II)NTA‐based EPR measurements to probe information beyond distance constraints.
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- Award ID(s):
- 2006154
- PAR ID:
- 10391970
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Protein Science
- Volume:
- 31
- Issue:
- 7
- ISSN:
- 0961-8368
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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