Structural changes in bacteriorhodopsin during ion transport at 2 Angstrom resolution
Structural changes in bacteriorhodopsin during ion transport at 2 Angstrom resolution
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DOI：
10.1126/science.286.5438.255
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发表时间：
1999-10-08
期刊：
影响因子：
56.9
通讯作者：
Lanyi, JK
中科院分区：
文献类型：
--
作者：
Luecke, H;Schobert, B;Lanyi, JK
光驱动质子泵细菌视紫红质的Asp（96）到Asn突变体及其在环境温度下由光照产生的M光中间体的晶体结构已被确定为分别为1.8和2.0埃的分辨率。捕获的光产物对应于运输周期中的晚M状态，即在质子转移到Asp（85）和质子释放到细胞外膜表面之后，但在去质子化的视网膜席夫碱的再质子化之前。其密度图描述了由其光异构化为13-顺式，15-反式诱导的靠近视黄醛的侧链的位移，以及氢键残基和结合水的三维网络的广泛重排，这解释了席夫碱和Asp的pK（a）值（其中K-a是酸常数）的变化（85）。检测到的结构变化表明，在活性位点保存能量，并确保质子易位的方向性的手段。
Crystal structures of the Asp(96) to Asn mutant of the light-driven proton pump bacteriorhodopsin and its M photointermediate produced by illumination at ambient temperature have been determined to 1.8 and 2.0 angstroms resolution, respectively. The trapped photoproduct corresponds to the Late M state in the transport cycle-that is, after proton transfer to Asp(85) and release of a proton to the extracellular membrane surface, but before reprotonation of the deprotonated retinal Schiff base. Its density map describes displacements of side chains near the retinal induced by its photoisomerization to 13-cis, 15-anti and an extensive rearrangement of the three-dimensional network of hydrogen-bonded residues and bound water that accounts for the changed pK(a) values (where K-a is the acid constant) of the Schiff base and Asp(85). The structural changes detected suggest the means for conserving energy at the active site and for ensuring the directionality of proton translocation.