Drug Discovery and Structural Biology group, Health Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad 44000, Pakistan.
Structural Biology Laboratory, Elettra-Sincrotrone Trieste, 34149 Trieste, Italy.
Int J Mol Sci. 2020 Jan 31;21(3):926. doi: 10.3390/ijms21030926.
The human zinc transporter 8 (hZnT8) plays important roles in the storage of insulin in the secretory vesicles of pancreatic β cells. hZnT8 consists of a transmembrane domain, with its N- and C-termini protruding into the cytoplasm. Interestingly, the exchange of arginine to tryptophan at position 325 in the C-terminal domain (CTD) increases the risk of developing type 2 diabetes mellitus (T2D). In the present study, the CTDs of hZnT8 (the wild-type (WT) and its disease risk variant (R325W)) were expressed, purified, and characterized in their native forms by biophysical techniques. The data reveal that the CTDs form tetramers which are stabilized by zinc binding, and exhibit negligible differences in their secondary structure content and zinc-binding affinities in solution. These findings provide the basis for conducting further structural studies aimed at unravelling the molecular mechanism underlying the increased susceptibility to develop T2D, which is modulated by the disease risk variant.
人锌转运蛋白 8（hZnT8）在胰腺β细胞分泌小泡中胰岛素的储存中发挥重要作用。hZnT8 由一个跨膜结构域组成，其 N 端和 C 端突入细胞质。有趣的是，C 末端结构域（CTD）中 325 位精氨酸突变为色氨酸会增加 2 型糖尿病（T2D）的发病风险。在本研究中，通过生物物理技术表达、纯化并以天然形式对 hZnT8 的 CTD（野生型（WT）及其疾病风险变异体（R325W））进行了表征。数据表明，CTD 形成四聚体，锌结合稳定四聚体，溶液中的二级结构含量和锌结合亲和力几乎没有差异。这些发现为进一步开展结构研究提供了基础，旨在揭示由疾病风险变异体调节的增加 T2D 易感性的分子机制。
