蛋白质二硫键异构酶与α-突触核蛋白的相互作用及对其聚集的影响

Inhibition ofα-Synuclein Aggregation by the Interaction Between Protein Disulfide Isomerase andα-Synuclein

α-突触核蛋白(α-synuclein,αsyn)的错误折叠和聚集是帕金森症的疾病特征.分子伴侣蛋白质二硫键异构酶(PDI)可在体外结合αsyn的N端并抑制其聚集,但PDI的识别机制至今仍不明确.我们通过液体核磁共振(NMR)实验,发现人源PDI b'xa'可结合αsyn的N端区域.此外,硫黄素T(ThT)荧光实验结果表明PDI b'xa'会显著抑制αsyn的聚集.我们进一步利用NMR滴定实验确定了PDI主要通过b'结构域的疏水空腔结合αsyn.最后,我们以此构建了PDI结合αsyn的对接模型,并提出了PDI抑制αsyn聚集的作用机理.这一工作为理解PDI抑制αsyn聚集提供了实验依据.

Abnormally misfolded and aggregatedα-synuclein(αsyn)is the hallmark of Parkinson's disease(PD).Molecular chaperone protein disulfide isomerase(PDI)has been shown to interact withαsyn and inhibit its aggregation in vitro,but the mechanism for the recognition ofαsyn by PDI is not yet clear.Herein,we used nuclear magnetic resonance(NMR)spectroscopy to identify that human PDI b'xa'bound with the N-terminal domain ofαsyn,and thioflavin T(ThT)fluorescence assay revealed that b'xa'domain of PDI significantly inhibitedαsyn aggregation.Furthermore,by using NMR titration,we observed that PDI bound toαsyn mainly through its hydrophobic cavity of the b'domain.Based on these findings,a docking model of PDI binding withαsyn was established and a possible mechanism of how PDI inhibitsαsyn aggregation was proposed.Our work provides experimental evidences for understanding the inhibitory role of PDI inαsyn aggregation.