Incorporation of glutamine repeats makes protein oligomerize: implications for neurodegenerative diseases.
Incorporation of glutamine repeats makes protein oligomerize: implications for neurodegenerative diseases.
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谷氨酰胺重复序列的掺入使蛋白质寡聚化：对神经退行性疾病的影响。
DOI：
10.1073/pnas.92.14.6509
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发表时间：
1995
影响因子：
11.1
通讯作者：
Perutz,M
中科院分区：
文献类型：
--
作者：
Stott,K;Blackburn,JM;Butler,PJ;Perutz,M
许多转录因子和一些其他蛋白质含有谷氨酰胺重复序列;它们的异常扩增与几种显性遗传性神经退行性疾病有关。已经发现聚（L-谷氨酰胺）单独形成β-链通过其酰胺基团之间的氢键保持在一起，我们推测谷氨酰胺重复序列可能形成极性拉链，这是蛋白质-蛋白质相互作用的一种不寻常的基序。为了验证这一假设，我们通过插入和替换将Gly-Gln 10-Gly肽改造到截短型胰凝乳蛋白酶抑制剂2（CI 2）（一种来自大麦种子的小蛋白质）的抑制环中。凝胶过滤将两种突变体抑制剂解析成至少三个部分，分析超离心鉴定为重组蛋白的单体、二聚体和三聚体;截短的野生型CI 2仅形成单体。二聚体和三聚体相对于野生型的CD差谱表明，它们的谷氨酰胺重复形成β-折叠片，而单体相对于野生型的那些更提示I型β-转角。所有三种级分的CD光谱即使在70 ° C下孵育后也保持不变;在该温度下，二聚体和三聚体均未解离。我们认为，所有三个馏分的稳定性是由于在寡聚体中或在由每个单体的单个谷氨酰胺重复形成的β-发夹内的谷氨酰胺重复的延伸链之间的氢键的多样性。当扩展的谷氨酰胺重复序列导致蛋白质彼此之间或与具有谷氨酰胺重复序列的其他蛋白质之间获得过高的亲和力时，可能会出现病理效应。
Many transcription factors and some other proteins contain glutamine repeats; their abnormal expansion has been linked to several dominantly inherited neuro-degenerative diseases. Having found that poly(L-glutamine) alone forms beta-strands held together by hydrogen bonds between their amide groups, we surmised that glutamine repeats may form polar zippers, an unusual motif for protein-protein interactions. To test this hypothesis, we have engineered a Gly-Gln10-Gly peptide into the inhibitory loop of truncated chymotrypsin inhibitor 2 (CI2), a small protein from barley seeds, by both insertion and replacement. Gel filtration resolved both mutant inhibitors into at least three fractions, which analytical ultracentrifugation identified as monomers, dimers, and trimers of the recombinant protein; the truncated wild-type CI2 formed only monomers. CD difference spectra of the dimers and trimers versus wild type indicated that their glutamine repeats formed beta-pleated sheets, while those of the monomers versus wild type were more suggestive of type I beta-turns. The CD spectra of all three fractions remained unchanged even after incubation at 70 degrees C; neither the dimers nor the trimers dissociated at this temperature. We argue that the stability of all three fractions is due to the multiplicity of hydrogen bonds between extended strands of glutamine repeats in the oligomers or within a beta-hairpin formed by the single glutamine repeat of each monomer. Pathological effects may arise when expanded glutamine repeats cause proteins to acquire excessively high affinities for each other or for other proteins with glutamine repeats.