Nat:细菌毛发控制着自然界“电网”开关 菌毛 呼出电子

顾汉现

Nature:细菌的“毛发”控制着自然界“电网”的开关 菌毛 呼出电子

环球科学

2021/09/07

论文
论文标题：Structure of Geobacter pili reveals secretory rather than nanowire behaviour
作者：Gu, Yangqi, Srikanth, Vishok, Salazar-Morales, Aldo I., Jain, Ruchi, O’Brien, J. Patrick, Yi, Sophia M., Soni, Rajesh Kumar, Samatey, Fadel A., Yalcin, Sibel Ebru, Malvankar, Nikhil S.

期刊：Nature
发表时间：2021/09/01
数字识别码：10.1038/s41586-021-03857-w
摘要：Extracellular electron transfer by Geobacter species through surface appendages known as microbial nanowires1 is important in a range of globally important environmental phenomena2, as well as for applications in bio-remediation, bioenergy, biofuels and bioelectronics. Since 2005, these nanowires have been thought to be type 4 pili composed solely of the PilA-N protein1. However, previous structural analyses have demonstrated that, during extracellular electron transfer, cells do not produce pili but rather nanowires made up of the cytochromes OmcS2,3 and OmcZ4. Here we show that Geobacter sulfurreducens binds PilA-N to PilA-C to assemble heterodimeric pili, which remain periplasmic under nanowire-producing conditions that require extracellular electron transfer5. Cryo-electron microscopy revealed that C-terminal residues of PilA-N stabilize its copolymerization with PilA-C (to form PilA-N–C) through electrostatic and hydrophobic interactions that position PilA-C along the outer surface of the filament. PilA-N–C filaments lack π-stacking of aromatic side chains and show a conductivity that is 20,000-fold lower than that of OmcZ nanowires. In contrast with surface-displayed type 4 pili, PilA-N–C filaments show structure, function and localization akin to those of type 2 secretion pseudopili6. The secretion of OmcS and OmcZ nanowires is lost when pilA-N is deleted and restored when PilA-N–C filaments are reconstituted. The substitution of pilA-N with the type 4 pili of other microorganisms also causes a loss of secretion of OmcZ nanowires. As all major phyla of prokaryotes use systems similar to type 4 pili, this nanowire translocation machinery may have a widespread effect in identifying the evolution and prevalence of diverse electron-transferring microorganisms and in determining nanowire assembly architecture for designing synthetic protein nanowires.

所属学科：
生物


图片来源：Nikhil Malvankar/Yale University



几乎所有的生物在将营养物质转化为能量时，都需要氧气来清除多余的电子。然而，生活在海底或地下的土壤细菌无法获得氧气，它们通过微小的蛋白质丝来释放多余的电子。这些细菌的蛋白质丝相互连接，仿佛由“纳米电线”组成了一张“电网”，渗透到土壤和海床中。发表在《自然》的一项研究揭示，一种隐藏在细菌内部的毛发状结构充当着“电网”的开关。



研究人员使用冷冻电子显微镜研究了这种毛发状结构，发现它由两种不同的蛋白质组成。毛发状结构本身并没有充当纳米电线，而是隐藏在细菌内部，在缺氧时像活塞一样泵出纳米电线，通过这个过程细菌“呼出”电子。研究人员称，他们正在寻求方法利用这种天然电网发电、生产生物燃料和能够自我修复的电子元件。

https://www.nature.com/articles/s41586-021-03857-w

https://www.linkresearcher.com/t ... d-ade6-92ce857d9b4b



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