1. School of Pharmacy, Tokyo University of Pharmacy and Life Science, Horinouchi, Hachioji, Tokyo, 192-0392 Japan1
2. Suntory Institute for Bioorganic Research, Wakayamadai, Shimamotocho, Mishima-gun, Osaka, 618-8503 Japan2
3. Department of Medical Microbiology, University of Gothenburg, Guldhedsgatan 10, S-41346 Gothenburg, Sweden3
4. School of Biosciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK4