posted on 2016-07-06, 00:00authored bySamuel
I. Mann, Tillmann Heinisch, Andrew C. Weitz, Michael P. Hendrich, Thomas
R. Ward, A. S. Borovik
Cupredoxins are electron-transfer
proteins that have active sites
containing a mononuclear Cu center with an unusual trigonal monopyramidal
structure (Type 1 Cu). A single Cu–Scys bond is
present within the trigonal plane that is responsible for its unique
physical properties. We demonstrate that a cysteine-containing variant
of streptavidin (Sav) can serve as a protein host to model the structure
and properties of Type 1 Cu sites. A series of artificial Cu proteins
are described that rely on Sav and a series of biotinylated synthetic
Cu complexes. Optical and EPR measurements highlight the presence
of a Cu–Scys bond, and XRD analysis provides structural
evidence. We further provide evidence that changes in the linker between
the biotin and Cu complex within the synthetic constructs allows for
small changes in the placement of Cu centers within Sav that have
dramatic effects on the structural and physical properties of the
resulting artificial metalloproteins. These findings highlight the
utility of the biotin-Sav technology as an approach for simulating
active sites of metalloproteins.