Mapping Precursor-binding Site on TatC Subunit of Twin Arginine-specific Protein Translocase by Site-specific Photo Cross-linking*
Mapping Precursor-binding Site on TatC Subunit of Twin Arginine-specific Protein Translocase by Site-specific Photo Cross-linking*
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DOI：
10.1074/jbc.m112.343798
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发表时间：
2012-02
期刊：
影响因子：
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通讯作者：
Stefan Zoufaly;J. Fröbel;Patrick H Rose;T. Flecken;C. Maurer;Michael Moser;Matthias Müller
中科院分区：
文献类型：
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作者：
Stefan Zoufaly;J. Fröbel;Patrick H Rose;T. Flecken;C. Maurer;Michael Moser;Matthias Müller
背景：TatA、TatB和TatC是Tat转座酶的亚基，允许折叠的前蛋白跨细胞膜运输。结果：我们发现了TatC位点与前蛋白TatA、TatB和TatC相互作用。结论：胞质N端和胞质第一个TatC环构成了双精氨酸识别位点的一部分。细菌、古生菌和植物叶绿体的一些分泌前体蛋白在其信号肽中具有保守的双精氨酸序列基序。许多这些前体蛋白通过特定的双精氨酸易位（Tat）机制以完全折叠的构象分泌。这种机器是由两种膜蛋白组成的高分子量复合物，一种是六螺旋的TatC蛋白，通常是一种或两种单跨膜蛋白，称为TatA和TatB。TatC先前已被证明参与双精氨酸信号肽的识别。我们对静息和易位条件下的大肠杆菌TatC蛋白进行了广泛的位点特异性交联分析。这种策略使我们能够将双精氨酸信号肽的识别位点定位到细胞质n端区域和TatC的第一个细胞质环。此外，还揭示了TatC、TatB和TatA之间的离散接触点。我们讨论了一个关于双精氨酸信号序列如何在Tat转位中被容纳的暂定模型。
Background: TatA, TatB, and TatC are subunits of the Tat translocase allowing transport of folded pre-proteins across cellular membranes Results: We identified TatC sites that interact with pre-proteins, TatA, TatB, and TatC Conclusion: The cytosolic N terminus and first cytosolic TatC loop constitute part of a twin arginine recognition site Significance: We developed a working model of how twin arginine pre-protein inserts into Tat translocase. A number of secreted precursor proteins of bacteria, archaea, and plant chloroplasts stand out by a conserved twin arginine-containing sequence motif in their signal peptides. Many of these precursor proteins are secreted in a completely folded conformation by specific twin arginine translocation (Tat) machineries. Tat machineries are high molecular mass complexes consisting of two types of membrane proteins, a hexahelical TatC protein, and usually one or two single-spanning membrane proteins, called TatA and TatB. TatC has previously been shown to be involved in the recognition of twin arginine signal peptides. We have performed an extensive site-specific cross-linking analysis of the Escherichia coli TatC protein under resting and translocating conditions. This strategy allowed us to map the recognition site for twin arginine signal peptides to the cytosolic N-terminal region and first cytosolic loop of TatC. In addition, discrete contact sites between TatC, TatB, and TatA were revealed. We discuss a tentative model of how a twin arginine signal sequence might be accommodated in the Tat translocase.