...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >Topology and Accessibility of the Transmembrane Helices and the Sensory Site in the Bifunctional Transporter DcuB of Escherichia coli
【24h】

Topology and Accessibility of the Transmembrane Helices and the Sensory Site in the Bifunctional Transporter DcuB of Escherichia coli

机译：大肠杆菌双功能转运蛋白DcuB中跨膜螺旋和感觉部位的拓扑结构和可及性

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

C_4-Dicarboxylate uptake transporter B (DcuB) of Escherichia coli is a bifunctional transporter that catalyzes fumarate/succinate antiport and serves as a cosensor of the sensor kinase DcuS. Sites and domains of DcuB were analyzed for their topology relative to the cytoplasmic or periplasmic side of the membrane and their accessibility to the water space. For the topology studies, DcuB was fused at 33 sites to the reporter enzymes PhoA and LacZ that are only active when located in the periplasm or the cytoplasm, respectively. The ratios of the PhoA and LacZ activities suggested the presence of 10 or 11 hydrophilic loops, and 11 or 12 R-helical transmembrane domains (TMDs). The central part of DcuB allowed no clear topology prediction with LacZ/PhoA fusions. The sites of DcuB accessible to the hydrophilic thiol reagent 4-acetamido-40-maleimidylstilbene-2,20-disulfonate (AMS) were determined with variants of DcuB that carried single Cys residues. After intact cells were labeled with the membrane-impermeable AMS, denatured cells were differentially labeled with the thiol reagent polyethylene-glycol-maleimide (PEGmal) and analyzed for a mass shift. From 35 positions 17 were accessible to AMS in intact bacteria. The model derived from topology and accessibility suggests 12TMDs for DcuB and a waterfilled cavity in its central part. The cavity ends with a cytoplasmic lid accessible to AMS from the periplasmic side. The sensory domain of DcuB is composed of cytoplasmic loop XI/XII and a membrane integral region with the regulatory residues Thr396/Asp398 and Lys353.
机译：大肠杆菌的C_4-二羧酸摄取转运蛋白B（DcuB）是双功能转运蛋白，可催化富马酸酯/琥珀酸酯的反向转运，并充当传感器激酶DcuS的共传感器。分析了DcuB的位点和域相对于膜的细胞质或周质侧的拓扑结构以及它们对水空间的可及性。对于拓扑研究，DcuB在33个位点分别与报道酶PhoA和LacZ融合，后者分别位于周质或细胞质中才有活性。 PhoA和LacZ活性的比率表明存在10或11个亲水环，以及11或12个R螺旋跨膜结构域（TMD）。 DcuB的中心部分不允许使用LacZ / PhoA融合进行清晰的拓扑预测。用携带单个Cys残基的DcuB变体确定了亲水性巯基试剂4-乙酰氨基-40-马来酰亚胺基苯乙烯-2,20-二磺酸盐（AMS）可访问的DcuB的位点。将完整的细胞用不透膜的AMS标记后，将变性的细胞用硫醇试剂聚乙二醇-马来酰亚胺（PEGmal）进行差异标记，并分析质量变化。 AMS可以从35个位置中获取完整细菌中的17个位置。从拓扑和可访问性得出的模型建议DcuB有12个TMD，在其中心部分有一个充满水的空腔。腔体的末端是一个胞质盖，从周质侧可进入AMS。 DcuB的感觉域由胞质环XI / XII和带有调控残基Thr396 / Asp398和Lys353的膜整合区组成。

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