Cyclophilin active site mutants have native prolyl isomerase activity with a protein substrate

FEBS Letters

Schmid, Franz X.²  Heitman, Joseph¹  Scholz, Christian²  Dolinski, Kara¹  Schindler, Thomas² 

[1] Departments of Genetics and Pharmacology, Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA;Biochemisches Laboratorium, Universität Bayreuth, D-95440 Bayreuth, Germany

关键词: Cyclophilin;    Immunophilin;    Prolyl isomerization;    Protein folding;    Mitochondria;    RNase T1;    ribonuclease T1;    RCM-(S54G/P55N)-RNase T1;    disulfide-reduced and S-carboxymethylated form of a variant of RNase T1 with Ser54 and Pro55 replaced by Gly and Asn;    respectively;    Cpr3;    mitochondrial cyclophilin of Saccharomyces cerevisiae;    GdmCl;    guanidinium chloride;   

DOI  :  10.1016/S0014-5793(97)00979-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The prolyl isomerase activity of cyclophilins is traditionally measured by an assay in which prolyl cis/trans isomerization in a chromogenic tetrapeptide is coupled with its isomer-specific cleavage by chymotrypsin. Two variants of mitochondrial cyclophilin with substitutions in the presumed active site (R73A and H144Q) are inactive in the protease-coupled assay, but show almost wild-type activity in an assay that is based on the catalysis of a proline-limited protein folding reaction. This prolyl isomerase assay is preferable, both because coupling with proteolysis is avoided and because an intact protein instead of a short peptide is used as a substrate. Possibly, some earlier conclusions about the catalytic mechanism and the involvement of the prolyl isomerase activity in the cellular function of immunophilins may need reevaluation.

【 授权许可】

Unknown