Lalaouna David, Fochesato Sylvain, Harir Mourad, Ortet Philippe, Schmitt-Kopplin Philippe, Heulin Thierry, Achouak Wafa
Aix Marseille Univ, CEA, CNRS, BIAM, Lab Microbial Ecology of the Rhizosphere (LEMiRE), F-13108 Saint-Paul-Lez-Durance, France.
Université de Strasbourg, CNRS, ARN UPR 9002, F-67000 Strasbourg, France.
Microorganisms. 2021 Jan 26;9(2):250. doi: 10.3390/microorganisms9020250.
In the beneficial plant root-associated strain NFM421, the GacS/GacA two-component system positively controls biofilm formation and the production of secondary metabolites through the synthesis of , and . Here, we evidenced the genetic amplification of Rsm sRNAs by the discovery of a novel 110-nt long sRNA encoding gene, , generated by the duplication of (formerly ). Like the others genes, its overexpression overrides the mutation. We explored the expression and the stability of , , and encoding genes under rich or nutrient-poor conditions, and showed that their amount is fine-tuned at the transcriptional and more interestingly at the post-transcriptional level. Unlike and , we noticed that the expression of and genes was exclusively GacA-dependent. The highest expression level and longest half-life for each sRNA were correlated with the highest ppGpp and cyclic-di-GMP levels and were recorded under nutrient-poor conditions. Together, these data support the view that the Rsm system in is likely linked to the stringent response, and seems to be required for bacterial adaptation to nutritional stress.
在有益的植物根系相关菌株NFM421中，GacS/GacA双组分系统通过合成 、 和 来正向调控生物膜形成和次级代谢产物的产生。在此，我们通过发现一个由 （原 ）复制产生的新型110 nt长的sRNA编码基因 ，证明了Rsm sRNA的基因扩增。与其他 基因一样，其过表达可克服 突变。我们探究了在丰富或营养匮乏条件下 、 、 和 编码基因的表达及稳定性，结果表明它们的数量在转录水平以及更有趣的是在转录后水平上得到了精细调节。与 和 不同，我们注意到 和 基因的表达完全依赖于GacA。每种sRNA的最高表达水平和最长半衰期与最高的ppGpp和环二鸟苷酸水平相关，且在营养匮乏条件下记录到这些情况。总之，这些数据支持这样一种观点，即 中的Rsm系统可能与严谨反应相关联，并且似乎是细菌适应营养胁迫所必需的。
