The effects of helix breaking mutations in the diphtheria toxin transmembrane domain helix layers of the fusion toxin DAB389IL-2
The effects of helix breaking mutations in the diphtheria toxin transmembrane domain helix layers of the fusion toxin DAB389IL-2
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DOI：
10.1093/protein/11.9.811
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发表时间：
1998-09-01
期刊：
影响因子：
--
通讯作者：
vanderSpek, JC
中科院分区：
文献类型：
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作者：
Hu, HY;Huynh, PD;vanderSpek, JC
融合蛋白毒素DAB（389）IL-2由白喉毒素的催化和跨膜结构域与人白细胞介素2（IL-2）遗传连接组成。该融合毒素对表达高亲和力形式的IL-2受体的真核细胞具有选择性毒性，并且中毒机制与天然白喉毒素相似。我们使用定点诱变引入Pro残基的跨膜结构域的三个螺旋层的每一个。虽然每个突变导致细胞毒活性的完全丧失，但发现单个突变体在平面脂质双层中的通道形成、结合亲和力和熔解温度方面有所不同。我们建议，三个螺旋层中的每一个都在催化结构域向细胞胞质溶胶的生产性递送中起着关键作用。
The fusion protein toxin DAB(389)IL-2 is composed of the catalytic and transmembrane domains of diphtheria toxin genetically linked to human interleukin 2 (IL-2). This fusion toxin is selectively toxic for eukaryotic cells which express the high-affinity form of the IL-2 receptor and the mechanism of intoxication parallels that of native diphtheria toxin. We used site-directed mutagenesis to introduce Pro residues into each of the three helical layers of the transmembrane domain. Although each of the mutations results in the complete loss of cytotoxic activity, individual mutants were found to vary with respect to channel formation in planar lipid bilayers, binding affinity and melting temperature. We propose that each of the three helix layers plays a critical role in the productive delivery of the catalytic domain to the cell cytosol.