Department of Cell and Molecular Biology, Biomedical Centre, Uppsala University, Box 596, 751 24, Uppsala, Sweden.
Department of Biotechnology, Central University of Haryana, Mahendergarh, 123031, India.
Sci Rep. 2021 May 12;11(1):10060. doi: 10.1038/s41598-021-89069-8.
Microorganisms survive stresses by alternating the expression of genes suitable for surviving the immediate and present danger and eventually adapt to new conditions. Many bacteria have evolved a multiprotein "molecular machinery" designated the "Stressosome" that integrates different stress signals and activates alternative sigma factors for appropriate downstream responses. We and others have identified orthologs of some of the Bacillus subtilis stressosome components, RsbR, RsbS, RsbT and RsbUVW in several mycobacteria and we have previously reported mutual interactions among the stressosome components RsbR, RsbS, RsbT and RsbUVW from Mycobacterium marinum. Here we provide evidence that "STAS" domains of both RsbR and RsbS are important for establishing the interaction and thus critical for stressosome assembly. Fluorescence microscopy further suggested co-localization of RsbR and RsbS in multiprotein complexes visible as co-localized fluorescent foci distributed at scattered locations in the M. marinum cytoplasm; the number, intensity and distribution of such foci changed in cells under stressed conditions. Finally, we provide bioinformatics data that 17 (of 244) mycobacteria, which lack the RsbRST genes, carry homologs of Bacillus cereus genes rsbK and rsbM indicating the existence of alternative σ activation pathways among mycobacteria.
微生物通过交替表达适合应对当前和当前危险的基因来生存，最终适应新的条件。许多细菌已经进化出一种多蛋白“分子机器”，称为“应激体”，它整合不同的应激信号，并激活替代 sigma 因子以进行适当的下游反应。我们和其他人已经在几种分枝杆菌中鉴定了芽孢杆菌应激体成分 RsbR、RsbS、RsbT 和 RsbUVW 的同源物，并且我们之前已经报道了来自海分枝杆菌的应激体成分 RsbR、RsbS、RsbT 和 RsbUVW 之间的相互作用。在这里，我们提供的证据表明 RsbR 和 RsbS 的“STAS”结构域对于建立相互作用是重要的，因此对于应激体组装是关键的。荧光显微镜进一步表明，RsbR 和 RsbS 的“STAS”结构域在多蛋白复合物中相互作用，这些复合物作为在海分枝杆菌细胞质中分布在分散位置的共定位荧光焦点可见；在应激条件下，这些焦点的数量、强度和分布发生了变化。最后，我们提供了生物信息学数据，表明 17 种（244 种）缺乏 RsbRST 基因的分枝杆菌携带蜡样芽孢杆菌基因 rsbK 和 rsbM 的同源物，这表明分枝杆菌之间存在替代σ激活途径。
