Multimer recognition and secretion by the non-classical secretion pathway in Bacillus subtilis.
Multimer recognition and secretion by the non-classical secretion pathway in Bacillus subtilis.
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枯草芽孢杆菌非经典分泌途径的多聚体识别和分泌
DOI：
10.1038/srep44023
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发表时间：
2017-03-09
影响因子：
4.6
通讯作者：
Zhang D
中科院分区：
文献类型：
--
作者：
Zhao L;Chen J;Sun J;Zhang D
非经典蛋白质分泌是细菌中常见的现象。然而，非经典分泌途径的选择原则仍不清楚。在这里，我们的实验数据，据我们所知，是第一个显示，折叠的多聚体蛋白可以识别和分泌的非经典分泌途径在枯草芽孢杆菌。我们研究了Ruminococcus sp.5_1_39BFAA（RDPE）胞质蛋白D-阿洛酮糖3-差向异构酶的分泌模式，发现其非经典分泌并不是简单的细胞裂解所致。截短变体的分析表明，C-和N-末端，和两个疏水结构域，是必需的结构稳定性和非经典分泌的RDPE。丙氨酸扫描突变的疏水片段的RDPE显示，疏水残基介导的平衡之间的折叠和未折叠的形式。报告mCherry和GFP与RDPE区域的融合显示其分泌需要完整的四聚体蛋白复合物。使用交联的四聚体，我们表明，折叠的四聚体RDPE可以分泌作为一个单一的单位。最后，我们提供的证据表明，非经典分泌途径对多聚体底物具有强烈的偏好，这些底物积累在两极和隔膜区域。总之，这些数据表明，多聚体识别机制可能适用于整个非经典分泌途径。
Non-classical protein secretion in bacteria is a common phenomenon. However, the selection principle for non-classical secretion pathways remains unclear. Here, our experimental data, to our knowledge, are the first to show that folded multimeric proteins can be recognized and excreted by a non-classical secretion pathway inBacillus subtilis. We explored the secretion pattern of a typical cytoplasmic protein D-psicose 3-epimerase fromRuminococcus sp. 5_1_39BFAA (RDPE), and showed that its non-classical secretion is not simply due to cell lysis. Analysis of truncation variants revealed that the C- and N-terminus, and two hydrophobic domains, are required for structural stability and non-classical secretion of RDPE. Alanine scanning mutagenesis of the hydrophobic segments of RDPE revealed that hydrophobic residues mediated the equilibrium between its folded and unfolded forms. Reporter mCherry and GFP fusions with RDPE regions show that its secretion requires an intact tetrameric protein complex. Using cross-linked tetramers, we show that folded tetrameric RDPE can be secreted as a single unit. Finally, we provide evidence that the non-classical secretion pathway has a strong preference for multimeric substrates, which accumulate at the poles and septum region. Altogether, these data show that a multimer recognition mechanism is likely applicable across the non-classical secretion pathway.