Qing Rui, Tao Fei, Chatterjee Pranam, Yang Gaojie, Han Qiuyi, Chung Haeyoon, Ni Jun, Suter Bernhard P, Kubicek Jan, Maertens Barbara, Schubert Thomas, Blackburn Camron, Zhang Shuguang
Media Lab, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
Laboratory of Food Microbial Technology, State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiaotong University, Shanghai 200240, China.
iScience. 2020 Oct 28;23(12):101670. doi: 10.1016/j.isci.2020.101670. eCollection 2020 Dec 18.
It was posited that functionalities of GPCRs require full-length sequences that are negated by residue deletions. Here we report that significantly truncated nfCCR5 and nfCXCR4 still bind native ligands. Receptor-ligand interactions were discovered from yeast 2-hybrid screening and confirmed by mating selection. Two nfCCR5 (SZ218a, SZ190b) and two nfCXCR4 (SZ158a, SZ146a) were expressed in . Synthesized receptors exhibited α-helical structures and bound respective ligands with reduced affinities. SZ190b and SZ158a were reconverted into non-QTY forms and expressed in HEK293T cells. Reconverted receptors localized on cell membranes and functioned as negative regulators for ligand-induced signaling when co-expressed with full-length receptors. CCR5-SZ190b individually can perform signaling at a reduced level with higher ligand concentration. Our findings provide insight into essential structural components for CCR5 and CXCR4 functionality, while raising the possibility that non-full-length receptors may be resulted from alternative splicing and that pseudo-genes in genomes may be present and functional in living organisms.
据推测，G蛋白偶联受体（GPCRs）的功能需要完整的序列，而残基缺失会使其丧失功能。在此，我们报告称，显著截短的nfCCR5和nfCXCR4仍能结合天然配体。通过酵母双杂交筛选发现了受体-配体相互作用，并通过交配选择得到证实。两种nfCCR5（SZ218a、SZ190b）和两种nfCXCR4（SZ158a、SZ146a）在……中表达。合成的受体呈现出α-螺旋结构，并以降低的亲和力结合各自的配体。SZ190b和SZ158a被重新转化为非QTY形式，并在HEK293T细胞中表达。重新转化的受体定位于细胞膜上，当与全长受体共表达时，作为配体诱导信号的负调节因子发挥作用。单独的CCR5-SZ190b在较高配体浓度下可在较低水平上进行信号传导。我们的研究结果为CCR5和CXCR4功能的基本结构成分提供了见解，同时增加了非全长受体可能由可变剪接产生以及基因组中的假基因可能在活生物体中存在并发挥功能的可能性。
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