Download MendeleyStructural characterization of the Cu(II)-NTA spin label on alpha-helices by X-ray crystallography and electron paramagnetic resonance.
Besaw, J.E., Reichenwallner, J., Chen, E.Y., Hermet-Teesalu, P., Tregubenko, A., Kim, K., Morizumi, T., Ustav Jr., M., Ernst, O.P.(2026) Structure 34: 645
- PubMed: 41794029 Search on PubMed
- DOI: https://doi.org/10.1016/j.str.2026.01.010
- Primary Citation Related Structures:
9D9J, 9DJA, 9DJB, 9DJC, 9DJD, 9DJE, 9DJF, 9DJG, 9DJH, 9DJI, 9DJJ, 9DJK, 9DJL, 9DJM, 9DJN, 9DJO, 9DJP, 9DJQ, 9DJR, 9DJS - PubMed Abstract:
Site-directed Cu(II)-labelling in pulsed electron paramagnetic resonance (EPR) spectroscopy has demonstrated narrow Cu(II)-Cu(II) distance distributions suitable to resolve subtle protein conformational changes. The high precision derives from a double histidine (dHis) mutation that effectively locks a Cu(II)-nitrilotriacetic acid (Cu(II)-NTA) moiety in place. To date, no structures featuring the dHis-Cu(II)-NTA motif have been resolved. This work presents the atomic-resolution X-ray crystal structures of seven α-helical dHis sites of T4 lysozyme (T4L) in the presence and absence of Cu(II)-NTA. Our research captured the rigid octahedral coordination of the dHis-Cu(II)-NTA complex as well as non-conventional binding modes, which provide valuable insight into dHis site selection. Pulsed EPR experiments on double dHis T4L mutants displayed remarkable agreement to the crystallography-derived distances. This research showcases the rigid configuration of the dHis-Cu(II)-NTA motif, providing geometric constraints that can be leveraged in modeling and molecular dynamics programs to extract protein structural details from EPR experiments.
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada. Electronic address: jessica.besaw@mail.utoronto.ca.
Organizational Affiliation:
