5.4.3) Lrp and ArcZ
In Erwinia amylovora , the causal agent of fire blight disease that devastates apple and pear trees, Lrp modulates several virulence-associated traits and it is post-transcriptionally regulated by the Hfq-dependent sRNA ArcZ (Schachterle and Sundin, 2019). ArcZ interacts with the 103-nt-long 5’UTR of lrp to destabiliselrp mRNA. ArcZ was shown to positively regulate the motility phenotype and the transcription of flagellar genes indirectly through Lrp, while directly repressing the translation of flhDC mRNA. This incoherent feed-forward loop could generate a uniquely shaped output pulse in flagellar motility in response to variations in Lrp quantity. Thus, Lrp could temporarily shift motility under specific environmental conditions, mostly through its regulation of flhDC . Other sRNAs, such as ArcZ, may be involved in lrp regulation, as described in E. amylovora . We can therefore postulate that post-transcriptional regulation of lrp involving sRNAs may be crucial, even if the sRNA varies.