Title | Mechanism underlying autoinducer recognition in the DPO-VqmA quorum-sensing pathway. |
Publication Type | Journal Article |
Year of Publication | 2020 |
Authors | Huang, X, Duddy, OP, Silpe, JE, Paczkowski, JE, Cong, J, Henke, BR, Bassler, BL |
Journal | J Biol Chem |
Volume | 295 |
Issue | 10 |
Pagination | 2916-2931 |
Date Published | 2020 Mar 06 |
ISSN | 1083-351X |
Keywords | Bacterial 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 |
Abstract | <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> |
DOI | 10.1074/jbc.RA119.012104 |
Alternate Journal | J Biol Chem |
PubMed ID | 31964715 |
PubMed Central ID | PMC7062168 |
Grant List | P30 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 |