Backbone and side chain dynamics of uncomplexed human adipocyte and muscle fatty acid-binding proteins
Backbone and side chain dynamics of uncomplexed human adipocyte and muscle fatty acid-binding proteins
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DOI：
10.1021/bi980203o
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发表时间：
1998-06-02
期刊：
影响因子：
2.9
通讯作者：
Farmer, BT
中科院分区：
文献类型：
--
作者：
Constantine, KL;Friedrichs, MS;Farmer, BT
脂肪细胞脂结合蛋白(A-LBP)和肌肉脂肪酸结合蛋白(M-FABP)是一个小分子(约15 kDa)胞浆蛋白家族的成员，参与脂肪酸和其他脂溶分子的代谢。尽管A-LBP和M-FABP具有很高的同源性(65%)和非常相似的结构，但它们表现出不同的配体结合特征。由于配体结合可能受到蛋白质固有的动力学性质的影响，我们研究了未复合(Apo)的人A-LBP和M-FABP的主链和侧链动力学，通过测量N-15T-1和T-2值以及{H-1}-N-15 NOES来表征骨架动力学。使用无模型谱密度函数和简化谱密度图对这些数据进行分析。通过测定(CH2H)-C-13-H-1-H-2基团的H-2T-1和T-1Rho驰豫时间来表征含甲基侧链的动力学。用无模型方法对H-2弛豫数据进行了分析。对于A-LBP，获得了111个残基的N-15松弛数据和42个甲基的H-2松弛数据。对于M-FABP。获得了111个残基的N-15松弛数据和53个甲基的H-2松弛数据。比较了这两种蛋白质的内在灵活性，特别强调了结合口袋残基。这两种蛋白质之间的相应残基之间有许多明显的动力学差异。特别是，与M-FABP相比，许多残基在A-LBP中显示出更大的主干皮秒到纳秒和/或微秒到毫秒的时间尺度迁移率，包括F57、K58和大多数α-螺旋2中的残基(残基28-35)。这一区域的动态变化可能对配体的选择性起到作用。排列在脂肪酸结合口袋内的侧链在两种蛋白质中都显示出广泛的运动限制。显示这两种蛋白质之间明显动力学差异的侧链包括残基20、29和51的侧链。这些信息为确定配体结合引起的动态变化提供了必要的基准，并最终可能导致对脂肪酸结合蛋白之间配体亲和力和选择性的更好理解。
Adipocyte lipid-binding protein (A-LBP) and muscle fatty acid-binding protein (M-FABP) are members of a family of small (similar to 15 kDa) cytosolic proteins that are involved in the metabolism of fatty acids and other lipid-soluble molecules. Although highly homologous (65%) and structurally very similar, A-LBP and M-FABP display distinct ligand binding characteristics. Since ligand binding may be influenced by intrinsic protein dynamical properties, we have characterized the backbone and side chain dynamics of uncomplexed (apo) human A-LBP and M-FABP, Backbone dynamics were characterized by measurements of N-15 T-1 and T-2 values and {H-1}-N-15 NOEs. These data were analyzed using model-free spectral density functions and reduced spectral density mapping. The dynamics of methyl-containing side chains were characterized by measurements of H-2 T-1 and T-1 rho relaxation times of (CH2H)-C-13-H-1-H-2 groups. The H-2 relaxation data were analyzed using the model-free approach. For A-LBP, N-15 relaxation data were obtained for 111 residues and H-2 relaxation data were obtained for 42 methyl groups. For M-FABP. N-15 relaxation data were obtained for 111 residues and H-2 relaxation data were obtained for 53 methyl groups. The intrinsic flexibilities of these two proteins are compared, with particular emphasis placed on binding pocket residues. There are a number of distinct dynamical differences among corresponding residues between the two proteins. In particular, many residues display greater backbone picosecond to nanosecond and/or microsecond to millisecond time scale mobility in A-LBP relative to M-FABP, including F57, K58, and most residues in alpha-helix 2 (residues 28-35). Variations in the dynamics of this region may play a role in ligand selectivity. The side chains lining the fatty acid binding pocket display a wide range of motional restriction in both proteins. Side chains showing distinct dynamical differences between the two proteins include those of residues 20, 29, and 51. This information provides a necessary benchmark for determining dynamical changes induced by ligand binding and may ultimately lead to an enhanced understanding of ligand affinity and selectivity among fatty acid-binding proteins.