来自Enterococcus hirae的V型Na+-ATPase的旋翼结构
Takeshi Murata1, Ichiro Yamato, Yoshimi Kakinuma
1Medical Research Council Dunn Human Nutrition Unit, Hills Road, Cambridge CB2 2XY, UK.
概括
Enterococcus hirae V型离子抽腺三酸酶 (Na+-ATPase) 有一个旋转环,其中有10个NtpK子单元. 每个子单元都包含一个对于酶功能至关重要的离子结合点.
科学领域:
- 生物化学 生物化学
- 分子生物学分子生物学
- 结构生物学 结构生物学
背景情况:
- 空腔型 (V型) 腺三酸盐酶 (ATPases) 是各种生物体中发现的必不可少的质子或离子.
- 来自Enterococcus hirae的V型Na+-ATPase在离子运输中发挥着至关重要的作用.
- 了解V型ATPase的结构和功能是理解细胞能量转导的关键.
研究的目的:
- 为了阐明Enterococcus hirae的V型Na+-ATPase的膜旋转环的结构组织.
- 为了确定NtpK子单元中的离子结合点.
- 研究特定残留物和结构特征在离子转位中的作用.
主要方法:
- 对V型Na+-ATPase旋转环的结构分析.
- 同类蛋白脂子单元 (NtpK) 的识别.
- 对跨膜α螺旋和离子结合位点的分析.
主要成果:
- 旋转器环由10个NtpK子单元组成,与已知的蛋白质脂类相同.
- 每个NtpK子单元都有四个跨膜α螺旋.
- 一个关键的离子结合点,涉及谷氨酸-139,位于螺旋体2和4之间.
- 离子结合部位可以通过NTPI子单元中的半通道进入.
结论:
- 来自E. hirae的V型Na+-ATPase旋转环的结构揭示了离子送的保存机制.
- 已确定的离子结合点及其相关残留物对Na+-ATPase活性至关重要.
- 转子和催化域之间的对称性不匹配是ATPases的保存特征.
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