THE MOTA PROTEIN OF ESCHERICHIA-COLI IS A PROTON-CONDUCTING COMPONENT OF THE FLAGELLAR MOTOR
THE MOTA PROTEIN OF ESCHERICHIA-COLI IS A PROTON-CONDUCTING COMPONENT OF THE FLAGELLAR MOTOR
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DOI：
10.1016/0092-8674(90)90595-6
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发表时间：
1990-02-09
期刊：
影响因子：
64.5
通讯作者：
BERG, HC
中科院分区：
文献类型：
--
作者：
BLAIR, DF;BERG, HC
分离并鉴定了在大肠杆菌中鞭毛旋转所必需的基因mota的一些突变体。许多突变是显性的，这是由于功能性和非功能性MOTA之间竞争鞭毛马达中有限数量的位置。发现了一种新的突变体，其鞭毛扭矩在低速时是正常的，但在高速时会减少。对这些突变体的氢同位素效应表明，MoTA催化质子转移。我们证实了早期的一个观察结果，即MOTA的过度生产会导致蛋白质在细胞膜上的积累，并导致生长速度显著下降。当MOTA的无功能突变变异体过度生产时，它们会在细胞膜上积累，但生长没有受到损害。这些结果还表明，MoTA传导质子。通过测量含有野生型或突变型Mota蛋白的囊泡的质子渗透率，证实了这一点。
A number of mutants of MotA, a gene necessary for flagellar rotation in E. coli were isolated and characterized. Many mutations were dominant, owing to competition between functional and nonfunctional MotA for a limited number of sites in the flagellar motor. A new class of mutant was discovered in which flagellar torque is normal at low speeds but reduced at high speeds. Hydrogen isotope effects on these mutants indicate that MotA catalyzes proton transfer. We confirmed an earlier observation that overproduction of MotA leads to accumulation of the protein in the cytoplasmic membrane and to significant decreases in growth rate. When nonfunctional mutant variants of MotA were overproduced instead, they accumulated in the cytoplasmic membrane, but growth was not impaired. These results also suggest that MotA conducts protons. This was confirmed by measuring the proton permeabilities of vesicles containing wild-type or mutant MotA proteins.