Decreased Amyloidogenicity Caused by Mutational Modulation of Surface Properties of the Immunoglobulin Light Chain BRE Variable Domain

详细信息    查看全文

• 作者：Yuta Kobayashi ; Hirotaka Tsutsumi ; Tetsuyuki Abe ; Kyohei Ikeda ; Yuki Tashiro ; Satoru Unzai ; Hironari Kamikubo ; Mikio Kataoka ; Hidekazu Hiroaki ; Daizo Hamada
• 刊名：Biochemistry
• 出版年：2014
• 出版时间：August 12, 2014
• 年：2014
• 卷：53
• 期：31
• 页码：5162-5173
• 全文大小：594K
• ISSN：1520-4995

文摘

Amyloid formation by immunoglobulin light chain (LC) proteins is associated with amyloid light chain (AL) amyloidosis. Destabilization of the native state of the variable domain of the LC (V_L) is known to be one of the critical factors in promoting the formation of amyloid fibrils. However, determining the key residues involved in this destabilization remains challenging, because of the existence of a number of intrinsic sequence variations within V_L. In this study, we identified the key residues for destabilization of the native state of amyloidogenic V_L in the LC of BRE by analyzing the stability of chimeric mutants of BRE and REI V_L; the latter immunoglobulin is not associated with AL amyloidosis. The results suggest that the surface-exposed residues N45 and D50 are the key residues in the destabilization of the native state of BRE V_L. Point mutations at the corresponding residues in REI V_L (K45N, E50D, and K45N/E50D) destabilized the native state and increased amyloidogenicity. However, the reverse mutations in BRE V_L (N45K, D50E, and N45K/D50E) re-established the native state and decreased amyloidogenicity. Thus, analyses using chimeras and point mutants successfully elucidated the key residues involved in BRE V_L destabilization and increased amyloidogenic propensity. These results also suggest that the modulation of surface properties of wild-type V_L may improve their stability and prevent the formation of amyloid fibrils.