Human heat shock protein 70 (Hsp70) as a peripheral membrane protein
Human heat shock protein 70 (Hsp70) as a peripheral membrane protein
复制标题
DOI：
10.1016/j.bbamem.2014.01.022
复制
发表时间：
2014-05-01
影响因子：
3.4
通讯作者：
Kinnunen, Paavo K. J.
中科院分区：
文献类型：
--
作者：
Mahalka, Ajay K.;Kirkegaard, Thomas;Kinnunen, Paavo K. J.
虽然热休克蛋白70（Hsp 70）的显著部分在溶酶体、线粒体和癌细胞的外表面中与膜缔合，但是相互作用的机制仍然难以捉摸，没有蛋白受体的确凿证据。热休克蛋白70（Hsp 70）的N端核苷酸结合域（NBD）和C端底物结合域（SBD）分别含有两个色氨酸（W 90和W580）。我们使用Hsp 70及其W 90 F和W580 F突变体，以及Hsp 70-Delta SBD和Hsp 70-Delta NBD构建体的荧光光谱研究表明，与脂质体的结合取决于它们的脂质组成，并且涉及NBD和SBD。Hsp 70与磷脂酰胆碱（PC）脂质体的缔合较弱，其Trps插入到双层烃区域中。在心磷脂（CL）、双单酰基甘油磷酸（BMP）或磷脂酰丝氨酸（PS）的存在下，Hsp 70附着于外周膜，而不穿透。我们的数据表明，Hsp 70的细胞器的分布是由其特定的脂质组成，与Hsp 70与上述脂质在线粒体，溶酶体，和癌细胞表面，分别。NBD和SBD通过延长的磷脂锚定与脂质连接，其中特定的酸性磷脂以延长的构象与Hsp 70缔合，其中酰基链插入Hsp 70内的疏水裂缝中，而其他链保留在双层中。这种锚定预期会导致Hsp 70在表面上的严格取向。我们的数据进一步表明，酸性磷脂诱导SBD过渡到熔融球状态，这可能是必不可少的，让SBD基板的相互作用也在疏水双层内部酰基链区域。(C)2014爱思唯尔有限公司版权所有。
While a significant fraction of heat shock protein 70 (Hsp70) is membrane associated in lysosomes, mitochondria, and the outer surface of cancer cells, the mechanisms of interaction have remained elusive, with no conclusive demonstration of a protein receptor. Hsp70 contains two Trps, W90 and W580, in its N-terminal nucleotide binding domain (NBD), and the C-terminal substrate binding domain (SBD), respectively. Our fluorescence spectroscopy study using Hsp70 and its W90F and W580F mutants, and Hsp70-Delta SBD and Hsp70-Delta NBD constructs, revealed that binding to liposomes depends on their lipid composition and involves both NBD and SBD. Association of Hsp70 with phosphatidylcholine (PC) liposomes is weak, with insertion of its Trps into the bilayer hydrocarbon region. In the presence of cardiolipin (CL), bis-monoacylglycero phosphate (BMP), or phosphatidylserine (PS) Hsp70 attaches to membranes peripherally, without penetration. Our data suggest that the organelle distribution of Hsp70 is determined by their specific lipid compositions, with Hsp70 associating with the above lipids in mitochondria, lysosomes, and the surface of cancer cells, respectively. NBD and SBD attach to lipids by extended phospholipid anchorage, with specific acidic phospholipids associating with Hsp70 in the extended conformation with acyl chains inserting into hydrophobic crevices within Hsp70, and other chains remaining in the bilayer. This anchorage is expected to cause a stringent orientation of Hsp70 on the surface. Our data further suggest that acidic phospholipids induce a transition of SBD into the molten globule state, which may be essential to allow SBD substrate interaction also within the hydrophobic bilayer interior acyl chain region. (C) 2014 Elsevier B.V. All rights reserved.