...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >Phosphorylation site mutants of the mannitol transport protein enzyme IImtl of Escherichia coli: studies on the interaction between the mannitol translocating C-domain and the phosphorylation site on the energy-coupling B-domain.
【24h】

Phosphorylation site mutants of the mannitol transport protein enzyme IImtl of Escherichia coli: studies on the interaction between the mannitol translocating C-domain and the phosphorylation site on the energy-coupling B-domain.

机译：大肠杆菌的甘露醇转运蛋白酶IImtl的磷酸化位点突变体：甘露醇易位C结构域和能量耦合B结构域的磷酸化位点之间相互作用的研究。

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Mannitol binding and translocation catalyzed by the C domain of the Escherichia coli mannitol transport protein enzyme IImtl is influenced by domain B. This interaction was studied by monitoring the effects of mutating the B domain phosphorylation site, C384, on the kinetics of mannitol binding to the C domain. The dissociation constants for mannitol to the C384 mutants in inside-out membrane vesicles varied from 45 nM for the wild-type enzyme to 306 nM for the mutants. The rate constants pertinent to the binding equilibrium were also altered by the mutations. The association rate of mannitol to the cytoplasmic binding site in the mutants was accelerated for all mutants. The exchange rate of bound mannitol on the wild-type enzyme was shown to be pH dependent with a pKa of approximately 8 and increasing rates at higher pH. This rate was increased for all the mutants, but the pKas differed for the various mutants. The exchange rate for binding to the isolated IICmtl, however, was not pH dependent and exhibited a low rate. Exchange measured at 4 degrees C showed that, of the two steps, binding and occlusion, involved in binding to wild-type EIImtl in inside-out vesicles, only one could be detected for the C384E and C384L mutants. This suggests that the mutations increased the rate of the occlusion step so that it was no longer separable from the initial binding step or that the mutations eliminated the occlusion step altogether. The change in the mannitol binding kinetics of the C domain indicates that the B and C domains of EIImtl influence each other's conformation.(ABSTRACT TRUNCATED AT 250 WORDS)
机译：大肠杆菌甘露醇转运蛋白酶IImtl的C结构域催化的甘露醇结合和易位受结构域B的影响。通过监测B结构域磷酸化位点C384突变对甘露醇结合到其上的动力学的影响，研究了这种相互作用。 C域。内向外膜囊泡中甘露醇与C384突变体的解离常数从野生型酶的45 nM到突变体的306 nM不等。与结合平衡有关的速率常数也因突变而改变。对于所有突变体，甘露醇与突变体中细胞质结合位点的缔合速率均得到加速。结合的甘露醇在野生型酶上的交换速率显示为pH依赖性，pKa约为8，并且在较高pH下速率增加。对于所有突变体，该速率均增加，但是对于各种突变体，pKas不同。然而，与分离的IICmtl结合的交换速率不是pH依赖性的并且表现出低的速率。在4℃下测量的交换表明，在结合和封闭两个步骤中，与内在外囊泡中的野生型EIImtl的结合有关，对于C384E和C384L突变体仅能检测到一个。这表明突变增加了闭塞步骤的速率，使得它不再与初始结合步骤分离，或者突变完全消除了闭塞步骤。 C结构域的甘露醇结合动力学的变化表明EIImtl的B结构域和C结构域会相互影响构象。（摘要截短为250字）

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号