The gene for cyclophilin (peptidyl-prolylcis-transisomerase) fromSchizosaccharomyces pombe

Cyclophilin (CPH) is an ubiquitous 17-kD cytosolic protein with high binding affinity for the immunosuppressant cyclosporin A (1). CPH is identical to peptidyl-prolyl cis-trans isomerase, an enzyme catalyzing the isomerisation of proline imidic peptide bonds in oligopeptides and accelerating the rate-limiting steps in the refolding of certain proteins in vitro (2, 3). We have used degenerate and inosine containing primers directed against regions conserved between human (4) and Saccharomyces cerevisiae (5, 6) CPH (AAC/TGGIACIGGIGGIAA and GTG/ATTIGGICCIGCG/ATT, corresponding to positions 211-227 and 320-304, respectively, of the human sequence) to amplify by polymerase chain reaction (PCR) a 110 bp fragment from 5. pombe DNA. Screening of a 5. pombe genomic library with the above fragment resulted in the isolation of two positive clones. The nucleotide and deduced amino acid sequence of one clone is shown in Fig. 1. Southern analysis indicated the presence of a single gene for CPH in S. pombe (data not shown). The deduced amino acid sequence is 68.3%, 79.0% and 70.4% identical to human (4), S. cerevisiae (5) and Neurospora crassa (7) cyclophilins, respectively. ACKNOWLEDGEMENTS