About the Authors
Department of Computational and Systems Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
Department of Biochemistry and Molecular Biology, and Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts, United States of America
The authors have declared that no competing interests exist.
Conceived and designed the experiments: YL IB. Performed the experiments: YL. Analyzed the data: YL LMG IB. Contributed reagents/materials/analysis tools: YL IB. Wrote the paper: YL LMG IB.