In bacteria, the 5′-end-dependent RNA degradation is triggered by the RNA pyrophosphohydrolase RppH converting tri/diphosphate to monophosphate transcripts. This study shows that in the soil bacterium Azotobacter vinelandii, inactivation of rppH gene negatively affected the production of bioplastic poly-β-hydroxybutyrate (PHB) by reducing the expression at the translational level of PhbR, the specific transcriptional activator of the phbBAC biosynthetic operon. The effect of RppH on the translation of phbR seemed to be exerted through the translational repressor RsmA, as the inactivation of rsmA in the rppH mutant restored the phbR expression. Interestingly, in Escherichia coli inactivation of rppH also affected the expression of CsrA, the RsmA homolog. The level of the csrA transcript was higher and more stable in the E. coli rppH mutant than in the wild type strain. Additionally, and in contrast to the csrA mutants that are known to have a defective swimming phenotype, the E. coli rppH mutant showed a hyper-swimming phenotype that was suppressed by a csrA mutation, and the AvRppH restored to wild type level the swimming phenotype to the E. coli rppH mutant. We propose that in both A. vinelandii and E. coli, RppH activity plays a role in the expression of the translational regulator protein RsmA/CsrA.

在细菌中，RNA焦磷酸水解酶RppH将三/二磷酸酯转化为单磷酸酯转录物，从而触发5'-端依赖性RNA降解。这项研究表明，在土壤细菌葡萄固氮菌中，rppH基因的失活通过降低PhbR的翻译水平上的表达来负面影响生物塑料-β-羟基丁酸（PHB）的产生.PhbR是phbBAC生物合成操纵子的特定转录激活因子。上的翻译RppH的效果phbR似乎通过翻译抑制RSMA施加，作为失活RSMA在rppH突变体恢复了phbR表达。有趣的是，在大肠杆菌中，rppH的失活也影响了RsmA同源物CsrA的表达。所述的电平CSRA转录物在更高和更稳定的大肠杆菌rppH突变体比野生型菌株。此外，与已知的游泳表型缺陷的csrA突变体相反，大肠杆菌rppH突变体显示出被csrA突变抑制的高游泳表型，Av RppH在游泳时恢复为野生型水平大肠杆菌rppH突变体的表型。我们建议在A. vinelandii和大肠杆菌RppH活性在翻译调节蛋白RsmA / CsrA的表达中起作用。