摘要
古紫质-4(archaerhodopsin-4,aR4)是一种存在于嗜盐菌(Halobacterium sp.)XZ515细胞膜上含有类胡萝卜素发色团的细菌类光敏受体蛋白,与细菌视紫红质(bacteriorhodopsin,bR)具有类似的三聚结构和光驱质子泵功能。已有研究表明,bR蛋白D螺旋上具有保守性的天冬氨酸115(aspartic acid 115,D115)的去质子化会影响其质子泵功能,但其等位残基D116在aR4中的作用尚未见报道,特别是与D螺旋存在相互作用的类胡萝卜素发色团是否会对其功能存在影响更不得而知。本研究通过基因定点突变技术将aR4中的D116突变为极性不同的N116和A116以及bR的等位突变,采用紫外-可见光吸收光谱、闪光光解光谱和酸碱滴定等方法对比研究D115/D116突变对bR和aR4结构及光循环动力学的影响。研究结果表明,D116在aR4中的作用与D115在bR中的作用有所不同,且受类胡萝卜素发色团菌红素的影响。本研究有助于进一步认识含类胡萝卜素发色团的光敏受体蛋白D螺旋和菌红素的作用,同时也为研究其他双发色团微生物视紫红质家族蛋白的结构功能提供依据。
Archaerorhodopsin-4(aR4)is a carotenoid chromophore containing microbial photoreceptor found in Halobacterium sp.XZ515.It has a similar trimeric structure and a light-driven proton pump function as bacteriorhodopsin(bR).Previous studies showed that the deprotonation of aspartic acid 115(D115),a highly conserved charged residue on helix D of bR,can affect its proton pump function.However,little is known about the functional role of its corresponding residue D116 in aR4,and especially nothing is clear about whether the carotenoid chromophore interacting with helix D influences its function.Here,we explore the functional similarity and difference of D115 and D116 during the photocycle of bR and aR4 through site-directed mutagenesis,UV-Vis absorption spectroscopy,flash-light induced photolysis spectroscopy,and pH titration measurements.Our results show that D116 plays different roles in aR4 than that of D115 in bR,and the carotenoid chromophore regulates its function in particular.This study clarifies our current understanding of the functional role of helix D and the carotenoid chromophore in aR4.It will lay a foundation for studying other dual-chromophore microbial rhodopsin family proteins.
作者
王菲
赵欣
Wang Fei;Zhao Xin(School of Physics and Electronic Science,East China Normal University,Shanghai Key Laboratory of Magnetic Resonance,Shanghai,200241)
出处
《基因组学与应用生物学》
CAS
CSCD
北大核心
2022年第9期1914-1926,共13页
Genomics and Applied Biology
基金
国家自然科学基金项目(21475045,22074040)
上海市自然科学基金项目(19ZR1416300)共同资助
