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
KeywordsBacterial Proteins, Binding Sites, Crystallography, X-Ray, DNA, Gene Expression Regulation, Bacterial, Ligands, Molecular Dynamics Simulation, Mutagenesis, Site-Directed, Protein Binding, Pyrazoles, Quorum Sensing, Signal Transduction, Structure-Activity Relationship, Transcription Factors, Vibrio cholerae

<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 ListP30 GM133893 / GM / NIGMS NIH HHS / United States
/ HHMI / Howard Hughes Medical Institute / United States
T32 GM007388 / GM / NIGMS NIH HHS / United States
P41 GM111244 / GM / NIGMS NIH HHS / United States
R37 GM065859 / GM / NIGMS NIH HHS / United States