The leader peptide peTrpL forms antibiotic-containing ribonucleoprotein complexes for posttranscriptional regulation of multiresistance genes

ABSTRACT: Bacterial ribosome-dependent attenuators are widespread posttranscriptional regulators. They harbour small upstream ORFs (uORFs) encoding leader peptides, for which no functions in trans are known yet. In the soil-dwelling plant symbiont Sinorhizobium meliloti, the tryptophan biosynthesis gene trpE(G) is preceded by the uORF trpL and is regulated by transcription attenuation according to tryptophan availability. However, trpLE(G) transcription is initiated independently of the tryptophan level in S. meliloti, thereby ensuring a largely tryptophan-independent production of the leader peptide peTrpL. Here we provide evidence for a tryptophan-independent role of peTrpL in trans. We found that peTrpL increases the resistance towards tetracycline, erythromycin, chloramphenicol and the flavonoid genistein, which are substrates of the major multidrug efflux pump SmeAB. Coimmunoprecipitation with 3×FLAG-peTrpL suggested smeR mRNA, which encodes the transcription repressor of smeABR, as a peptide target. Indeed, upon antibiotic exposure, smeR mRNA was destabilized and smeA stabilized in a peTrpL-dependent manner, showing that peTrpL acts in the differential regulation of smeABR. Further, smeR mRNA was coimmunoprecipitated with 3×FLAG-peTrpL in antibiotic-dependent ribonucleoprotein (ARNP) complexes, which in addition contained an antibiotic-induced antisense RNA complementary to smeR. In vitro ARNP reconstitution revealed that the above antibiotics and genistein directly support complex formation. A specific region of the antisense RNA was identified as a seed region for ARNP assembly in vitro. Altogether, our data show that peTrpL is involved in a mechanism for direct utilization of antimicrobial compounds in posttranscriptional regulation of multiresistance genes. We also show that the role of peTrpL in resistance is conserved in other Alphaproteobacteria

INSTRUMENT(S): LTQ Orbitrap, TSQ Vantage

ORGANISM(S): Rhizobium Meliloti (ensifer Meliloti) (sinorhizobium Meliloti)

SUBMITTER: Sandra Maass  

LAB HEAD: Dörte Becher

PROVIDER: PXD018342 | Pride | 2020-05-19

REPOSITORIES: Pride