Structural basis of transport of lysophospholipids by human serum albumin
Structural basis of transport of lysophospholipids by human serum albumin
复制标题
人血清白蛋白转运溶血磷脂的结构基础
DOI：
10.1042/bj20090913
复制
发表时间：
2009-10-01
影响因子：
4.1
通讯作者：
Huang, Mingdong
中科院分区：
文献类型：
--
作者：
Guo, Shihui;Shi, Xiaoli;Huang, Mingdong
溶血磷脂在细胞信号转导中起重要作用，并且涉及许多生物过程，包括肿瘤发生、血管生成、免疫、动脉粥样硬化、动脉硬化、癌症和神经元存活。溶血磷脂的细胞内转运是通过FA（脂肪酸）结合蛋白。溶血磷脂也存在于细胞外空间。然而，溶血磷脂在细胞外空间的运输机制是未知的。人血清白蛋白（HSA）是血浆中含量最丰富的载体蛋白，对药物的吸收、分布、代谢和排泄起着重要作用。本文以溶血磷脂酰乙醇胺（LPE）为配体，通过荧光猝灭和晶体学方法研究了溶血磷脂与人血清白蛋白的相互作用。荧光测量显示LPE与HSA结合，Kd（解离常数）为5.6 μ W。FA（肉豆蔻酸酯）的存在降低了这种结合亲和力（Kd为12.9 μ M）。此外，我们确定了与肉豆蔻酸酯和LPE复合的HSA的晶体结构，并表明LPE结合在位于亚结构域IIA的Sudlow位点I。LPE占据了Sudlow位点1的三个子位点中的两个，其中LPE酰基链占据了Sudlow位点I的疏水底部，极性头部基团位于Sudlow位点I的入口区域，指向溶剂。LPE在HSA中的这种取向表明HSA能够容纳其他溶血磷脂和磷脂。该研究提供了HSA-溶血磷脂相互作用的结构信息，并可能有助于我们了解溶血磷脂的运输和分布。
Lysophospholipids play important roles in cellular signal transduction and are implicated in many biological processes, including tumorigenesis, angiogenesis, immunity, atherosclerosis, arteriosclerosis, cancer and neuronal survival. The intracellular transport of lysophospholipids is through FA (fatty acid)-binding protein. Lysophospholipids are also found in the extracellular space. However, the transport mechanism of lysophospholipids in the extracellular space is unknown. HSA (human serum albumin) is the most abundant carrier protein in blood plasma and plays an important role in determining the absorption, distribution, metabolism and excretion of drugs. In the present study, LPE (lysophosphatidylethanolamine) was used as the ligand to analyse the interaction of lysophospholipids with HSA by fluorescence quenching and crystallography. Fluorescence measurement showed that LPE binds to HSA with a K-d (dissociation constant) of 5.6 mu W. The presence of FA (myristate) decreases this binding affinity (K-d of 12.9 mu M). Moreover, we determined the crystal structure of HSA in complex with both myristate and LPE and showed that LPE binds at Sudlow site I located in subdomain IIA. LPE occupies two of the three subsites in Sudlow site 1, with the LPE acyl chain occupying the hydrophobic bottom of Sudlow site I and the polar head group located at Sudlow site I entrance region pointing to the solvent. This orientation of LPE in HSA suggests that HSA is capable of accommodating other lysophospholipids and phospholipids. The study provides structural information on HSA-lysophospholipid interaction and may facilitate our understanding of the transport and distribution of lysophospholipids.