1. Center for Advanced Biotechnology and Medicine and Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey 08854, Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey 08854, and Institute for Cellular and Molecular Biology, Section of Microbiology and Molecular Genetics, University of Texas at Austin, Austin, Texas 78746