[1] Joint Ctr Struct Genom, La Jolla, CA USA
[2] SLAC Natl Accelerator Lab, SSRL, Menlo Pk, CA USA
[3] Univ Paris Sud, Lab Enveloppes Bacteriennes & Antibiot, IBBMC, Orsay, France
[4] CNRS, Orsay, France
[5] Scripps Res Inst, Dept Mol Biol, La Jolla, CA 92037 USA