1. Department
of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States
2. Institute
for Genomic Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
3. Department
of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, United States
4. Department
of Microbiology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States