Substitution of amino acids in helix F of bacteriorhodopsin: effects on the photochemical cycle.
Substitution of amino acids in helix F of bacteriorhodopsin: effects on the photochemical cycle.
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细菌视紫红质螺旋 F 中氨基酸的取代：对光化学循环的影响。
DOI：
10.1021/bi00452a022
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发表时间：
1989
期刊：
影响因子：
2.9
通讯作者：
Rothschild,KJ
中科院分区：
文献类型：
--
作者：
Ahl,PL;Stern,LJ;Mogi,T;Khorana,HG;Rothschild,KJ
波士顿大学物理学和生理学系，590 Commonwealth Avenue，Boston，马萨诸塞州02215，以及马萨诸塞州理工学院生物学和化学系，剑桥，马萨诸塞州02139，1989年4月18日接收; 1989年7月21日接收修订版摘要：研究了细菌视紫红质F螺旋氨基酸取代对该光驱动质子泵光循环的影响。Ser-183-Ala和Glu-194-Gln突变体的光循环性质类似于大肠杆菌中产生的野生型细菌视紫红质和盐生盐杆菌的细菌视紫红质。Phe取代Trp-182或Trp-189显著降低了光循环细菌视紫红质的分数。氨基酸取代Tyr-185-Phe和Ser-193-Ala实质上增加了光循环的寿命，而实质上不增加M光循环中间体的寿命。用Pro-186-Gly取代也获得了类似的结果。相反，用较大的Leu取代Pro-186则抑制了M光循环中间体的形成。这些结果与低温紫外/可见和傅立叶变换红外差光谱所提出的具有Trp-182、Tyr-185、Pro-186和Trp-189形成的结合口袋的结构模型一致。细菌视紫红质（bR）1是盐生盐杆菌紫色膜中的光驱动质子泵。氨基酸序列含有七个标记为AG的疏水区，其对应于七个跨膜螺旋2（Hen-derson & Unwin，1975; Khorana等人，1979; Ovchinnikov等人，1979; Huang等人，1982年）。发色团，全反式-视黄醛，在螺旋G中通过共价键与Lys-216连接。
Departments of Physics and Physiology, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, and Departments of Biology and Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 Received April 18, 1989; Revised Manuscript Received July 21, 1989 abstract: The effects of amino acid substitutions in helix F of bacteriorhodopsin on the photocycle of this light-driven proton pump were studied. The photocycles of Ser-183—Ala and Glu-194—Gin mutants were qualitatively similar to that of wild-type bacteriorhodopsinproduced in Escherichia coli and bacteriorhodopsin from Halobacterium halobium. The substitution of a Phe for either Trp-182 or Trp-189 significantly reduced the fraction of photocycling bacteriorhodopsin. The amino acid substitutions Tyr-185—Phe and Ser-193—Ala substantially increased the lifetime of the photocycle without substantially increasing the lifetime of the M photocycle intermediate. Similar results were also obtained with the Pro-186—Gly substitution. In contrast, replacing Pro-186 with the larger residue Leu inhibited the formation of the M photocycle in-termediate. These results are consistent with a structural model of the retinal-binding pocket suggested by low-temperature UV/visible and Fourier transform infrared difference spectroscopies that has Trp-182, Tyr-185, Pro-186, and Trp-189 forming part of the binding pocket.Bacteriorhodopsin (bR) 1 is a light-driven proton pump in the purple membrane of Halobacterium halobium. Theamino acid sequence contains seven hydrophobic regions labeled AG that correspond to the seven transmembrane helices2 (Hen-derson & Unwin, 1975; Khorana et al., 1979; Ovchinnikov et al., 1979; Huang et al., 1982). The chromophore, all-trans-retinal, is covalently linked to Lys-216 in helix G through a