Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.
EMBO J. 2010 Jan 20;29(2):327-39. doi: 10.1038/emboj.2009.358. Epub 2009 Dec 3.
The cytoskeleton has a key function in the temporal and spatial organization of both prokaryotic and eukaryotic cells. Here, we report the identification of a new class of polymer-forming proteins, termed bactofilins, that are widely conserved among bacteria. In Caulobacter crescentus, two bactofilin paralogues cooperate to form a sheet-like structure lining the cytoplasmic membrane in proximity of the stalked cell pole. These assemblies mediate polar localization of a peptidoglycan synthase involved in stalk morphogenesis, thus complementing the function of the actin-like cytoskeleton and the cell division machinery in the regulation of cell wall biogenesis. In other bacteria, bactofilins can establish rod-shaped filaments or associate with the cell division apparatus, indicating considerable structural and functional flexibility. Bactofilins polymerize spontaneously in the absence of additional cofactors in vitro, forming stable ribbon- or rod-like filament bundles. Our results suggest that these structures have evolved as an alternative to intermediate filaments, serving as versatile molecular scaffolds in a variety of cellular pathways.
细胞骨架在原核细胞和真核细胞的时空组织中具有关键功能。在这里，我们报告了一类新的聚合物形成蛋白的鉴定，这些蛋白被称为细菌丝蛋白，它们在细菌中广泛保守。在新月柄杆菌中，两个细菌丝蛋白的同源物合作形成一个片状结构，排列在靠近菌柄细胞极的细胞质膜附近。这些组装体介导参与菌柄形态发生的肽聚糖合酶的极性定位，从而补充了肌动蛋白样细胞骨架和细胞分裂机制在细胞壁生物发生中的调节功能。在其他细菌中，细菌丝蛋白可以形成杆状纤维或与细胞分裂装置结合，表明其具有相当大的结构和功能灵活性。细菌丝蛋白在体外无其他辅助因子的情况下自发聚合，形成稳定的带状或杆状纤维束。我们的结果表明，这些结构是作为中间纤维的替代物进化而来的，作为各种细胞途径中的多功能分子支架。
