Details

Autor(en) / Beteiligte

• Steiner, Elisabeth
• Shilling, Rebecca E
• Richter, Anja M
• Schmid, Nadine
• Fazli, Mustafa
• Kaever, Volkhard
• Jenal, Urs
• Tolker-Nielsen, Tim
• Eberl, Leo

Titel

The BDSF quorum sensing receptor RpfR regulates Bep exopolysaccharide synthesis in Burkholderia cenocepacia via interaction with the transcriptional regulator BerB

Ist Teil von

• NPJ biofilms and microbiomes, 2022-11, Vol.8 (1), p.93-93, Article 93

Ort / Verlag

London: Nature Publishing Group

Erscheinungsjahr

2022

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• Abstract The polysaccharide Bep is essential for in vitro biofilm formation of the opportunistic pathogen Burkholderia cenocepacia . We found that the Burkholderia diffusible signaling factor (BDSF) quorum sensing receptor RpfR is a negative regulator of the bep gene cluster in B. cenocepacia . An rpfR mutant formed wrinkled colonies, whereas additional mutations in the bep genes or known bep regulators like berA and berB restored the wild-type smooth colony morphology. We found that there is a good correlation between intracellular c-di-GMP levels and bep expression when the c-di-GMP level is increased or decreased through ectopic expression of a diguanylate cyclase or a c-di-GMP phosphodiesterase, respectively. However, when the intracellular c-di-GMP level is changed by site directed mutagenesis of the EAL or GGDEF domain of RpfR there is no correlation between intracellular c-di-GMP levels and bep expression. Except for rpfR, deletion mutants of all 25 c-di-GMP phosphodiesterase and diguanylate cyclase genes encoded by B. cenocepacia showed no change to berA and bep gene expression. Moreover, bacterial two-hybrid assays provided evidence that RpfR and BerB physically interact and give specificity to the regulation of the bep genes. We suggest a model where RpfR binds BerB at low c-di-GMP levels to sequester this RpoN-dependent activator to an RpfR/RpfF complex. If the c-di-GMP levels rise, possibly by the enzymatic action of RpfR, BerB binds c-di-GMP and is released from the RpfR/RpfF complex and associates with RpoN to activate transcription of berA , and the BerA protein subsequently activates transcription of the bep genes.