Institute of Pharmacology and the Gaston H. Glock Research Laboratories for Exploratory Drug Development, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.
Department of Theoretical and Computational Biophysics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
Protein Sci. 2024 Jan;33(1):e4842. doi: 10.1002/pro.4842.
In chordates, energy buffering is achieved in part through phosphocreatine, which requires cellular uptake of creatine by the membrane-embedded creatine transporter (CRT1/SLC6A8). Mutations in human slc6a8 lead to creatine transporter deficiency syndrome, for which there is only limited treatment. Here, we used a combined homology modeling, molecular dynamics, and experimental approach to generate a structural model of CRT1. Our observations support the following conclusions: contrary to previous proposals, C144, a key residue in the substrate binding site, is not present in a charged state. Similarly, the side chain D458 must be present in a protonated form to maintain the structural integrity of CRT1. Finally, we identified that the interaction chain Y148-creatine-Na is essential to the process of occlusion, which occurs via a "hold-and-pull" mechanism. The model should be useful to study the impact of disease-associated point mutations on the folding of CRT1 and identify approaches which correct folding-deficient mutants.
在脊索动物中，能量缓冲部分通过磷酸肌酸实现，这需要细胞膜嵌入的肌酸转运蛋白（CRT1/SLC6A8）将肌酸摄取到细胞内。人类 slc6a8 基因突变导致肌酸转运蛋白缺乏综合征，对此只有有限的治疗方法。在这里，我们使用了组合同源建模、分子动力学和实验方法来生成 CRT1 的结构模型。我们的观察结果支持以下结论：与之前的提议相反，底物结合位点中的关键残基 C144 不存在带电荷状态。同样，侧链 D458 必须呈质子化形式，以维持 CRT1 的结构完整性。最后，我们确定了相互作用链 Y148-肌酸-Na 对于闭塞过程是必不可少的，该过程通过“保持和拉动”机制发生。该模型应该有助于研究与疾病相关的点突变对 CRT1 折叠的影响，并确定纠正折叠缺陷突变体的方法。
