一个Na+独立的氨基酸载体的结构和机制
Paul L Shaffer1, April Goehring, Aruna Shankaranarayanan
1Vollum Institute, Oregon Health and Science University, 3181 Southwest Sam Jackson Park Road, Portland, OR 97239, USA.
Science (New York, N.Y.)
|July 18, 2009
概括
氨基酸载体ApcT的晶体结构揭示了质子合运输的机制. 一个氨酸残留物,类似于其他载体中的离子位点,是这个过程的关键.
科学领域:
- 生物化学 生物化学
- 结构生物学 结构生物学
- 膜运输 运输 膜运输
背景情况:
- 氨基酸,聚胺和有机化物 (APC) 运输体是关键的二次运输体,参与营养吸收,废物清除和维持细胞平衡.
- 了解APC传送器功能的结构基础对于破译细胞传输机制至关重要.
研究的目的:
- 为了确定ApcT的apo状态的高分辨率晶体结构,一个质子合的氨基酸载体.
- 阐明ApcT运输机制的基础结构特征及其与其他二次运输商的关系.
主要方法:
- 采用X射线晶体学,以2.35安格斯特罗姆分辨率获得apo-ApcT的晶体结构.
- 生物信息分析和结构比较被用来确定关键的功能残留物和保存的运输原理.
主要成果:
- 阿波-ApcT的2.35安格斯特罗姆晶体结构揭示了12个跨膜螺旋束,结构上与LeuT传送器相似.
- 鉴定出一个氨酸残留物 (Lys-158) 的位置与 LeuT 中的 Na2 离子结合位相似,这表明它在质子合中发挥了作用.
- 该结构呈现出面向内部的形状,这是封闭或运输后状态的特征.
结论:
- ApcT的结构为对联氨基酸运输的机制提供了关键的见解.
- 氨酸-158被认为是质子转位的核心,在功能上模仿离子在相关载体中的作用.
- 这项研究突出了质子和合的二次传送器之间的保存机械原理.
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