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Essential role of Pro 74 in stefin B amyloid-fibril formation: Dual action of cyclophilin A on the process |
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| Authors: | Aida Smajlovi? Selma Berbi? Magda Tušek-?nidari? Saša Jenko-Kokalj Eva ?erovnik |
| Institution: | a Department of Biochemistry, Farmaceutical Faculty, University of Tuzla, Univerzitetska 8, 75000 Tuzla, Bosnia and Herzegovina b Max Planck Research Unit for Enzymology of Protein Folding, Weinbergweg 22, 06120 Halle/Saale, Germany c Department of Plant Physiology and Biotechnology, National Institute of Biology, Ve?na pot 111, 1000 Ljubljana, Slovenia d Department of Biochemistry, Molecular and Structural Biology, Jo?ef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia |
| Abstract: | We report that Pro74 in human stefin B is critical for fibril formation and that proline isomerization plays an important role. The stefin B P74S mutant did not fibrillate over the time of observation at 25 °C, and it exhibited a prolonged lag phase at 30 °C and 37 °C. The peptidyl prolyl cis/trans isomerase cyclophilin A, when added to the wild-type protein, exerted two effects: it prolonged the lag phase and increased the yield and length of the fibrils. Addition of the inactive cyclophilin A R55A variant still resulted in a prolonged lag phase but did not mediate the increase of the final fibril yield. These results demonstrate that peptidyl prolyl cis/trans isomerism is rate-limiting in stefin B fibril formation. |
| Keywords: | TFE 2 2 2-trifluoroethanol TEM transmission electron microscopy ThT thioflavin T PPI peptidyl-prolyl-cis/trans isomerase CAB carbonic anhydrase B CD circular dichroism |
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