多细胞蓝细菌,像Nostoc标点符号,依靠间隔连接进行细胞-细胞通讯,这对于协调各种生理过程至关重要,包括N2固定杂环的分化,类似孢子的akinetes,和hormogonia-短,对分散重要的能动细丝。在这项研究中,我们在功能上表征蛋白质,由Npun_F4142基因编码,在随机诱变方法中,最初显示出与运动相关的功能。重建的Npun_F4142敲除突变体表现出进一步不同的表型性状,包括运动性显著降低的激素形成改变,无法区分杂环和细丝断裂。出于这个原因,我们将蛋白质命名为FraI(片段化表型)。该突变体显示严重受损的细胞间通讯,由于间隔细胞壁中几乎完全没有纳米孔阵列,这是间隔连接的重要组成部分。尽管缺乏沟通,ΔfraI突变体中的hormogonia保持运动性和趋光行为,即使不如野生型(WT)明显。这表明了一种跨间隔接合处协调运动的替代机制。我们的研究强调了FraI在纳米孔形成和细胞分化中的重要性,并为中隔连接的形成和通讯在蓝藻各种分化特征中的重要性提供了额外的证据。这些发现有助于更深入地了解管理多细胞蓝藻行为的调控网络,对更广泛地了解微生物多细胞性具有重要意义。
目的:形成细丝的蓝细菌Nostocpunctiforme是研究细胞分化的有价值的模型,包括固氮杂环和激素的形成。Hormogonia细丝在传播和植物定植中起着至关重要的作用,通过大气固氮提供氮源,因此对无肥农业抱有希望。允许向阳性信号均匀运动的hormogonia细胞之间的协调仍然知之甚少。这项研究调查了间隔连接介导的通讯在激素分化和运动性中的作用,通过研究交流明显受损的ΔfraI突变体。令人惊讶的是,受损的通信不会取消同步灯丝运动,建议另一种协调机制。这些发现加深了我们对蓝细菌生物学的理解,并对原核生物的多细胞行为具有更广泛的意义。
Multicellular cyanobacteria, like Nostoc punctiforme, rely on septal junctions for cell-cell communication, which is crucial for coordinating various physiological processes including differentiation of N2-fixing heterocysts, spore-like akinetes, and hormogonia-short, motile filaments important for dispersal. In this study, we functionally characterize a protein, encoded by gene Npun_F4142, which in a random mutagenesis approach, initially showed a motility-related function. The reconstructed Npun_F4142 knockout mutant exhibits further distinct phenotypic traits, including altered hormogonia formation with significant reduced motility, inability to differentiate heterocysts and filament fragmentation. For that reason, we named the protein FraI (fragmentation phenotype). The mutant displays severely impaired cell-cell communication, due to almost complete absence of the nanopore array in the septal cell wall, which is an essential part of the septal junctions. Despite lack of communication, hormogonia in the ΔfraI mutant maintain motility and phototactic behavior, even though less pronounced than the wild type (WT). This suggests an alternative mechanism for coordinated movement beyond septal junctions. Our study underscores the significance of FraI in nanopore formation and cell differentiation, and provides additional evidence for the importance of septal junction formation and communication in various differentiation traits of cyanobacteria. The findings contribute to a deeper understanding of the regulatory networks governing multicellular cyanobacterial behavior, with implications for broader insights into microbial multicellularity.
OBJECTIVE: The filament-forming cyanobacterium Nostoc punctiforme serves as a valuable model for studying cell differentiation, including the formation of nitrogen-fixing heterocysts and hormogonia. Hormogonia filaments play a crucial role in dispersal and plant colonization, providing a nitrogen source through atmospheric nitrogen fixation, thus holding promise for fertilizer-free agriculture. The coordination among the hormogonia cells enabling uniform movement toward the positive signal remains poorly understood. This study investigates the role of septal junction-mediated communication in hormogonia differentiation and motility, by studying a ΔfraI mutant with significantly impaired communication. Surprisingly, impaired communication does not abolish synchronized filament movement, suggesting an alternative coordination mechanism. These findings deepen our understanding of cyanobacterial biology and have broader implications for multicellular behavior in prokaryotes.