演題概要

ポスター発表

第1日 6月17日(水)  P会場

Native MSによるプロテアソームα7サブユニットの自己会合状態の解析

(1自然科学研究機構2名市大院薬3阪大院工)
o石井健太郎1矢木宏和2加藤晃一1,2内山進3

Native mass spectrometry is the method that enables molecular mass measurements of proteins under non-denaturing conditions. Therefore native mass spectrometry can be a powerful tool to characterize non-covalently associated oligomeric states of protein complexes. The proteasome is a huge oligomeric protein complex and has a protein-degradation activity against ubiquitin-tagged proteins. The assembly mechanisms of the proteasome remain to be solved. Our research aim is to clarify the dynamic assembly process of the proteasome complex. It has been known that the 20S core particle is composed of two α-rings and two β-rings. In the mature proteasome, α-ring is constituted from 7 types of subunits, α1-α7. Whereas, our solution scattering data showed that the α7 spontaneously forms homotetradecamer that assumes a double-ring structure composed of two heptameric rings. In this study, we applied native mass spectrometry to analyze the oligomeric state of α7. We successfully obtained mass spectrum of α7 oligomer. The determined mass (408,587 Da) of the α7 oligomer clearly indicates the stable formation of α7 tetradecamer. We also identified an α7 homoheptamer with a molecular mass of 192,530 Da. These results are consistent with the solution scattering observation that tetradecameric α7 double-ring was composed of two heptameric rings.