SECONDARY STRUCTURE AND BACKBONE RESONANCE ASSIGNMENTS OF THE PERIPLASMIC CYCLOPHILIN TYPE PEPTIDYL-PROLYL ISOMERASE FROM ESCHERICHIA-COLI

Proton, carbon-13, and nitrogen-15 sequence-specific backbone assignme nts have been obtained for the periplasmic cyclophilin type cis-trans peptidyl-prolyl isomerase from Escherichia coli (167 residues, M(r) = 18 244). Assignments were obtained using both H-1, c-13, and N-15 trip le-resonance and H-1 and N-15 double-resonance three-dimensional (3D) NMR spectroscopy at pH 6.2, 25-degrees-C. Complete or partial residue- specific assignments have been obtained for 165 of the 167 residues. T he secondary structure has been characterized using long- and medium-r ange NOEs. The protein consists of an eight-stranded anti-parallel bet a-sheet and two helices. The overall topology of E. coli cyclophilin i s similar to that of human T-cell cyclophilin. Sequence alignment with human T-cell cyclophilin based on secondary structure homology implic ates several residues in E. coli cyclophilin that may be crucial for b inding the peptide substrate AC-A-A-P-A-AMC and the immunosuppressive drug cyclosporin A.