Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Norwich, NR4-7HU, UK.
Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Pavillon Roger-Gaudry, 2900, boulevard Édouard-Montpetit, C.P. 6128, Succursale Centre-ville, Montréal, QC, H3C 3J7, Canada.
Nat Commun. 2022 Jan 10;13(1):71. doi: 10.1038/s41467-021-27638-1.
Filamentous actinobacteria such as Streptomyces undergo two distinct modes of cell division, leading to partitioning of growing hyphae into multicellular compartments via cross-walls, and to septation and release of unicellular spores. Specific determinants for cross-wall formation and the importance of hyphal compartmentalization for Streptomyces development are largely unknown. Here we show that SepX, an actinobacterial-specific protein, is crucial for both cell division modes in Streptomyces venezuelae. Importantly, we find that sepX-deficient mutants grow without cross-walls and that this substantially impairs the fitness of colonies and the coordinated progression through the developmental life cycle. Protein interaction studies and live-cell imaging suggest that SepX contributes to the stabilization of the divisome, a mechanism that also requires the dynamin-like protein DynB. Thus, our work identifies an important determinant for cell division in Streptomyces that is required for cellular development and sporulation.
丝状放线菌（如链霉菌）经历两种不同的细胞分裂模式，通过细胞壁将生长中的菌丝分隔成多细胞隔室，并通过隔膜将单细胞孢子分隔释放。然而，对于细胞壁形成的特定决定因素以及菌丝隔室化对链霉菌发育的重要性，我们知之甚少。在这里，我们表明放线菌特异性蛋白 SepX 对于链霉菌的两种细胞分裂模式都是至关重要的。重要的是，我们发现 sepX 缺陷型突变体在没有细胞壁的情况下生长，这大大削弱了菌落的适应性和通过发育生命周期的协调进展。蛋白质相互作用研究和活细胞成像表明，SepX 有助于分裂体的稳定，这一机制还需要类似于动力蛋白的蛋白 DynB。因此，我们的工作确定了链霉菌细胞分裂的一个重要决定因素，该因素对于细胞发育和孢子形成是必需的。
