Spatial Clustering of the Curlin Secretion Lipoprotein Requires Curli Fiber Assembly
Spatial Clustering of the Curlin Secretion Lipoprotein Requires Curli Fiber Assembly
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DOI：
10.1128/jb.01244-08
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发表时间：
2009-01-15
影响因子：
3.2
通讯作者：
Chapman, Matthew R.
中科院分区：
文献类型：
--
作者：
Epstein, Elisabeth Ashman;Reizian, Margeaux A.;Chapman, Matthew R.
革兰氏阴性细菌组装功能性淀粉样蛋白表面纤维，称为卷曲。CsgB使主要卷曲亚基蛋白CsgA成核成细胞表面上的自繁殖淀粉样纤维。CsgG脂蛋白足以使卷曲蛋白转运穿过外膜，并被假设为卷曲纤维分泌和组装复合物的中心分子。我们测试的假设，curli分泌蛋白，CsgG，被限制到某些地区的细胞，以促进相互作用的CsgA和CsgB在curli组装。在这里，电子显微镜分析卷曲生产菌株表明，相对较少的细胞在人口接触卷曲纤维和卷曲从空间上离散的点在细胞表面上发出。显微镜分析表明，CsgG表面暴露和卷曲纤维周围的空间聚集。CsgG定位到外膜和暴露的表面结构域不依赖于任何其他CSG编码的蛋白质，但CsgG的聚类需要CSG编码的蛋白质CsgE，CsgF，CsgA和CsgB。CsgG在所有的csg突变株中形成稳定的寡聚体，但这些寡聚体与野生型细胞中组装的CsgG复合物不同。最后，我们发现，有效的纤维组装所需的空间集群的CsgG。这些结果表明一个新的模型，其中卷曲纤维的形成是空间协调与CsgG组装装置。
Gram-negative bacteria assemble functional amyloid surface fibers called curli. CsgB nucleates the major curli subunit protein, CsgA, into a self-propagating amyloid fiber on the cell surface. The CsgG lipoprotein is sufficient for curlin transport across the outer membrane and is hypothesized to be the central molecule of the curli fiber secretion and assembly complex. We tested the hypothesis that the curli secretion protein, CsgG, was restricted to certain areas of the cell to promote the interaction of CsgA and CsgB during curli assembly. Here, electron microscopic analysis of curli-producing strains showed that relatively few cells in the population contacted curli fibers and that curli emanated from spatially discrete points on the cell surface. Microscopic analysis revealed that CsgG was surface exposed and spatially clustered around curli fibers. CsgG localization to the outer membrane and exposure of the surface domain were not dependent on any other csg-encoded protein, but the clustering of CsgG required the csg-encoded proteins CsgE, CsgF, CsgA, and CsgB. CsgG formed stable oligomers in all the csg mutant strains, but these oligomers were distinct from the CsgG complexes assembled in wild-type cells. Finally, we found that efficient fiber assembly was required for the spatial clustering of CsgG. These results suggest a new model where curli fiber formation is spatially coordinated with the CsgG assembly apparatus.