1. Department of Biochemistry, University of Johannesburg, Corner Kingsway and University Roads, P.O. Box 524, Auckland Park, Johannesburg 2006, South Africa
2. Department of Molecular and Cell Biology, University of the Witwatersrand, 1 Jan Smuts Avenue, Braamfontein, Johannesburg 2000, South Africa
3. Department of Structural Biology and Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee 38105, United States