Affiliation: | (1) Department of Microbiology, University of Groningen, Kerklaan 30, NL-9751 NN Haren, The Netherlands;(2) Department of Biochemistry, University of Groningen, Nijenborgh 16, NL-9747 AG Groningen, The Netherlands;(3) Keck Laboratories 138-78, California Institute of Technology, 91125 Pasadena, CA, USA;(4) Present address: Department of Microbiology, The Ohio State University, 484 West 12th Avenue, 43210-1292 Columbus, OH, USA |