Control of mRNA translation is a crucial regulatory mechanism used by bacteria to respond to their environment. In the soil bacterium Pseudomonas fluorescens, RimK modifies the C-terminus of ribosomal protein RpsF to influence important aspects of rhizosphere colonisation through proteome remodelling. In this study, we show that RimK activity is itself under complex, multifactorial control by the co-transcribed phosphodiesterase trigger enzyme (RimA) and a polyglutamate-specific protease (RimB). Furthermore, biochemical experimentation and mathematical modelling reveal a role for the nucleotide second messenger cyclic-di-GMP in coordinating these activities. Active ribosome regulation by RimK occurs by two main routes: indirectly, through changes in the abundance of the global translational regulator Hfq and directly, with translation of surface attachment factors, amino acid transporters and key secreted molecules linked specifically to RpsF modification. Our findings show that post-translational ribosomal modification functions as a rapid-response mechanism that tunes global gene translation in response to environmental signals.

mRNA翻译的控制是细菌用来响应其环境的关键调节机制。在土壤细菌中荧光假单胞菌，RimK修饰核糖体蛋白RpsF的C末端，通过蛋白质组重塑影响根际定殖的重要方面。在这项研究中，我们表明RimK活性本身受复杂的，多因素控制的共转录的磷酸二酯酶触发酶（RimA）和聚谷氨酸特异性蛋白酶（RimB）。此外，生化实验和数学建模揭示了核苷酸第二信使环-di-GMP在协调这些活动中的作用。RimK对活性核糖体的调节主要通过两种途径发生：间接改变全局翻译调节因子Hfq的丰度，直接改变表面附着因子，氨基酸转运蛋白和与RpsF修饰相关的关键分泌分子的翻译。