Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
College of Life and Environmental Sciences, Geoffrey Pope, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
Nat Commun. 2020 May 6;11(1):2231. doi: 10.1038/s41467-020-15650-w.
Type IV pili are flexible filaments on the surface of bacteria, consisting of a helical assembly of pilin proteins. They are involved in bacterial motility (twitching), surface adhesion, biofilm formation and DNA uptake (natural transformation). Here, we use cryo-electron microscopy and mass spectrometry to show that the bacterium Thermus thermophilus produces two forms of type IV pilus ('wide' and 'narrow'), differing in structure and protein composition. Wide pili are composed of the major pilin PilA4, while narrow pili are composed of a so-far uncharacterized pilin which we name PilA5. Functional experiments indicate that PilA4 is required for natural transformation, while PilA5 is important for twitching motility.
IV 型菌毛是细菌表面的柔性细丝，由菌毛蛋白的螺旋组装而成。它们参与细菌的运动（蠕动）、表面粘附、生物膜形成和 DNA 摄取（自然转化）。在这里，我们使用低温电子显微镜和质谱法表明，嗜热栖热菌产生两种形式的 IV 型菌毛（“宽”和“窄”），在结构和蛋白质组成上有所不同。宽菌毛由主要菌毛 PilA4 组成，而窄菌毛由一种迄今尚未表征的菌毛组成，我们将其命名为 PilA5。功能实验表明，PilA4 是自然转化所必需的，而 PilA5 对蠕动运动很重要。
