Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
J Bacteriol. 2024 Jun 20;206(6):e0008924. doi: 10.1128/jb.00089-24. Epub 2024 May 31.
Many prokaryotes use swimming motility to move toward favorable conditions and escape adverse surroundings. Regulatory mechanisms governing bacterial flagella-driven motility are well-established; however, little is yet known about the regulation underlying swimming motility propelled by the archaeal cell surface structure, the archaella. Previous research showed that the deletion of the adhesion pilins (PilA1-6), subunits of the type IV pili cell surface structure, renders the model archaeon non-motile. In this study, we used ethyl methanesulfonate mutagenesis and a motility assay to identify motile suppressors of the ∆[] strain. Of the eight suppressors identified, six contain missense mutations in archaella biosynthesis genes, and expression of and mutant constructs in the respective multi-deletion strains ∆[]∆ and ∆[]∆ confirmed their role in suppressing the ∆[] motility defect. Additionally, three suppressors harbor co-occurring disruptive missense and nonsense mutations in , a gene encoding a proposed regulatory protein. A deletion of resulted in hypermotility, while expression in wild-type cells led to decreased motility. Moreover, quantitative real-time PCR analysis revealed that in wild-type cells, higher expression levels of , , and the archaellin gene were observed in motile early-log phase rod-shaped cells compared to non-motile mid-log phase disk-shaped cells. Conversely, ∆ cells, which form rods during both early- and mid-log phases, exhibited similar expression levels of genes in both growth phases. Our findings contribute to a deeper understanding of the mechanisms governing archaeal motility, highlighting the involvement of ArlI, ArlJ, and CirA in pilin-mediated motility regulation.IMPORTANCEArchaea are close relatives of eukaryotes and play crucial ecological roles. Certain behaviors, such as swimming motility, are thought to be important for archaeal environmental adaptation. Archaella, the archaeal motility appendages, are evolutionarily distinct from bacterial flagella, and the regulatory mechanisms driving archaeal motility are largely unknown. Previous research has linked the loss of type IV pili subunits to archaeal motility suppression. This study reveals three proteins involved in pilin-mediated motility regulation, offering a deeper understanding of motility regulation in this understudied domain while also paving the way for uncovering novel mechanisms that govern archaeal motility. Understanding archaeal cellular processes will help elucidate the ecological roles of archaea as well as the evolution of these processes across domains.
许多原核生物利用游泳运动向有利条件移动,并逃避不利环境。调节细菌鞭毛驱动运动的机制已得到很好的建立;然而,对于由古菌细胞表面结构——古菌鞭毛驱动的游泳运动的调节机制,我们知之甚少。先前的研究表明,缺失粘附菌毛(PilA1-6),即 IV 型菌毛细胞表面结构的亚基,会使模式古菌失去运动能力。在这项研究中,我们使用乙磺酸乙酯诱变和运动性测定来鉴定缺失 [] 菌株的运动性抑制子。在鉴定的八个抑制子中,有六个含有古菌生物合成基因的错义突变,并且在各自的多缺失菌株 []∆ 和 []∆ 中表达 和 突变体构建体证实了它们在抑制 [] 运动缺陷中的作用。此外,三个抑制子在编码假定调节蛋白的基因 中同时含有破坏性的错义和无义突变。 的缺失导致超运动性,而在野生型细胞中表达 则导致运动性降低。此外,定量实时 PCR 分析显示,在野生型细胞中,与非运动性中对数期盘状细胞相比,早期对数期杆状细胞中观察到更高水平的 、 和古菌菌毛基因 的表达。相反,在早期和中期对数阶段都形成杆状的 ∆ 细胞在两个生长阶段的 基因表达水平相似。我们的发现有助于更深入地了解调节古菌运动的机制,强调了 ArlI、ArlJ 和 CirA 在菌毛介导的运动调节中的作用。
重要性:古菌是真核生物的近亲,在生态中起着至关重要的作用。某些行为,如游泳运动,被认为对古菌的环境适应很重要。古菌鞭毛,古菌的运动附属物,与细菌鞭毛在进化上有很大的不同,而驱动古菌运动的调节机制在很大程度上是未知的。先前的研究将 IV 型菌毛亚基的缺失与古菌运动抑制联系起来。本研究揭示了三个参与菌毛介导的运动调节的 蛋白,这为深入了解这一研究不足的领域的运动调节提供了帮助,同时也为揭示控制古菌运动的新机制铺平了道路。了解古菌的细胞过程将有助于阐明古菌作为生态角色以及这些过程在不同领域的进化。
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