Molecular basis of metal-ion selectivity and zeptomolar sensitivity by CueRChangela, A., Chen, K., Xue, Y., Holschen, J., Outten, C.E., O'Halloran, T.V., Mondragon, A.
(2003) Science 301: 1383-1387
- PubMed: 12958362
- DOI: https://doi.org/10.1126/science.1085950
- Primary Citation of Related Structures:
1Q05, 1Q06, 1Q07, 1Q08, 1Q09, 1Q0A
- PubMed Abstract:
The earliest of a series of copper efflux genes in Escherichia coli are controlled by CueR, a member of the MerR family of transcriptional activators. Thermodynamic calibration of CueR reveals a zeptomolar (10(-21) molar) sensitivity to free Cu+, which is far less than one atom per cell. Atomic details of this extraordinary sensitivity and selectivity for +1transition-metal ions are revealed by comparing the crystal structures of CueR and a Zn2+-sensing homolog, ZntR. An unusual buried metal-receptor site in CueR restricts the metal to a linear, two-coordinate geometry and uses helix-dipole and hydrogen-bonding interactions to enhance metal binding. This binding mode is rare among metalloproteins but well suited for an ultrasensitive genetic switch.
Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, 2205Tech Drive, Evanston, IL 60208, USA.