1. Key Laboratory of Combinatorial Biosynthesis and Drug Discovery Wuhan University) Ministry of Education, and School of Pharmaceutical Sciences Wuhan University No. 185 East Lake Road Wuhan 430071 P. R. China
2. College of Chemistry and Molecular Sciences Wuhan University No. 299 Bayi Road Wuhan 430072 P. R. China
3. Current address: Singapore Institute of Food and Biotechnology Innovation Agency for Science, Technology, and Research (A*STAR) Singapore Singapore
4. Department of Biochemistry University of Cambridge No. 80 Tennis Court Road Cambridge CB2 1GA UK