ORIENTATION OF FUNCTIONAL AND NONFUNCTIONAL PTS PERMEASE SIGNAL SEQUENCES IN LIPID BILAYERS - A POLARIZED ATTENUATED TOTAL-REFLECTION INFRARED STUDY
ORIENTATION OF FUNCTIONAL AND NONFUNCTIONAL PTS PERMEASE SIGNAL SEQUENCES IN LIPID BILAYERS - A POLARIZED ATTENUATED TOTAL-REFLECTION INFRARED STUDY
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DOI：
10.1021/bi00081a017
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发表时间：
1993-08-03
期刊：
影响因子：
2.9
通讯作者：
TATULIAN, SA
中科院分区：
文献类型：
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作者：
TAMM, LK;TATULIAN, SA
将细菌糖磷酸转移酶系统的甘露醇和葡糖醇专一性膜蛋白N端23和22位残基的合成肽分别掺入锗平板上的单一平面磷脂双层膜中。记录了偏振衰减全反射红外光谱，并由测量的二向色性比得到了有序参数。在膜中形成两亲性α-螺旋的两个野生型多肽的有序参数为-0.4~-0.5，表明α-螺旋长轴平行于膜表面优先排列。甘露醇渗透酶序列中丝氨酸-3或天冬氨酸-4被脯氨酸(S3P和D4P)或赖氨酸(D4K)取代，但大部分仍为α-螺旋的无功能突变多肽的多肽顺序参数接近于零，表明这些多肽在脂质双层中高度无序。当膜中的多肽浓度较低时，膜中的脂类排列有序，但在较高浓度时，脂类变得无序。这种脂质紊乱的影响在D4K突变体中比野生型甘露醇肽更明显。
Synthetic peptides corresponding to the N-terminal 23 and 22 residues, respectively, of two integral plasma membrane proteins of Escherichia coli, namely the mannitol- and glucitol-specific permeases of the bacterial sugar phosphotransferase system, were incorporated into single planar phospholipid bilayers supported on germanium plates. Polarized attenuated total reflection infrared spectra were recorded, and order parameters were derived from the measured dichroic ratios. The order parameters of the two wild-type peptides which form amphiphilic alpha-helices in membranes were -0.4 to -0.5, indicating a preferential alignment of the alpha-helix long axis parallel to the membrane surface. Nonfunctional mutant peptides of the mannitol permease sequence in which serine-3 or aspartate-4 were substituted with prolines (S3P and D4P) or lysine (D4K), but which were still largely alpha-helical, exhibited peptide order parameters close to zero, indicating a high degree of disorder of these peptides in the lipid bilayers. The lipid was well ordered at low concentrations of peptides in the membranes but became disordered at high peptide concentrations. This effect of lipid disordering was more pronounced for the D4K mutant than for the wild-type mannitol peptide.