1. Department of BiochemistryEmory University School of MedicineAtlantaGeorgiaUSA
2. Department of BiologyEmory University School of MedicineAtlantaGeorgiaUSA
3. Department of Biological SciencesUniversity of IowaIowa CityIA52242‐1324USA
4. Department of Molecular Genetics and MicrobiologyUniversity of Florida College of MedicineGainesvilleFL32610‐0266USA