Mechanism underlying autoinducer recognition in the DPO-VqmA quorum-sensing pathway.

TitleMechanism underlying autoinducer recognition in the DPO-VqmA quorum-sensing pathway.
Publication TypeJournal Article
Year of Publication2020
AuthorsHuang, X, Duddy, OP, Silpe, JE, Paczkowski, JE, Cong, J, Henke, BR, Bassler, BL
JournalJ Biol Chem
Date Published2020 Mar 06

<p>Quorum sensing is a bacterial communication process whereby bacteria produce, release, and detect extracellular signaling molecules called autoinducers to coordinate collective behaviors. In the pathogen , the quorum-sensing autoinducer 3,5-dimethyl-pyrazin-2-ol (DPO) binds the receptor and transcription factor VqmA. The DPO-VqmA complex activates transcription of , encoding the VqmR small RNA, which represses genes required for biofilm formation and virulence factor production. Here, we show that VqmA is soluble and properly folded and activates basal-level transcription of its target in the absence of DPO. VqmA transcriptional activity is increased in response to increasing concentrations of DPO, allowing VqmA to drive the quorum-sensing transition at high cell densities. We solved the DPO-VqmA crystal structure to 2.0 Å resolution and compared it with existing structures to understand the conformational changes VqmA undergoes upon DNA binding. Analysis of DPO analogs showed that a hydroxyl or carbonyl group at the 2'-position is critical for binding to VqmA. The proposed DPO precursor, a linear molecule, -alanyl-aminoacetone (Ala-AA), also bound and activated VqmA. Results from site-directed mutagenesis and competitive ligand-binding analyses revealed that DPO and Ala-AA occupy the same binding site. In summary, our structure-function analysis identifies key features required for VqmA activation and DNA binding and establishes that, whereas VqmA binds two different ligands, VqmA does not require a bound ligand for folding or basal transcriptional activity. However, bound ligand is required for maximal activity.</p>

Alternate JournalJ. Biol. Chem.
PubMed ID31964715
PubMed Central IDPMC7062168
Grant ListP41 GM111244 / GM / NIGMS NIH HHS / United States
R37 GM065859 / GM / NIGMS NIH HHS / United States
T32 GM007388 / GM / NIGMS NIH HHS / United States