Related Experiment Video
Updated: Jun 10, 2026
An Ecdysone Receptor-based Singular Gene Switch for Deliberate Expression of Transgene with Robustness, Reversibility, and Negligible Leakiness
Published on: May 7, 2018
Urate is a ligand for the transcriptional regulator PecS
1Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
Abstract:
PecS is a member of the MarR (multiple antibiotic resistance regulator) family, which has been shown in Erwinia to regulate the expression of virulence genes. MarR homologs typically bind a small molecule ligand, resulting in attenuated DNA binding. For PecS, the natural ligand has not been identified. We have previously shown that urate is a ligand for the Deinococcus radiodurans-encoded MarR homolog HucR (hypothetical uricase regulator) and identified residues responsible for ligand binding. We show here that all four residues involved in urate binding and propagation of conformational changes to DNA recognition helices are conserved in PecS homologs, suggesting that urate is the ligand for PecS. Consistent with this prediction, Agrobacterium tumefaciens PecS specifically binds urate, and urate attenuates DNA binding in vitro. PecS binds two operator sites in the intergenic region between the divergent pecS gene and pecM genes, one of which features two partially overlapping repeats to which PecS binds as a dimer on opposite faces of the duplex. Notably, urate dissociates PecS from cognate DNA, allowing transcription of both genes in vivo. Taken together, our data show that urate is a ligand for PecS and suggest that urate serves a novel function in signaling the colonization of a host plant.
Insights
Urate is identified as the natural ligand for PecS, a regulator of virulence genes. Urate binding to PecS attenuates its DNA binding, enabling gene expression and signaling host plant colonization.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- PecS belongs to the MarR family of regulators, known to control virulence gene expression.
- MarR homologs typically bind small molecules, altering their DNA-binding affinity.
- The natural ligand for PecS has remained unidentified.
Purpose of the Study:
- To identify the natural ligand for PecS.
- To investigate the mechanism of PecS-ligand interaction and its effect on DNA binding.
- To explore the role of PecS-ligand interaction in bacterial virulence and host colonization.
Main Methods:
- Sequence analysis of PecS homologs to identify conserved residues.
- In vitro binding assays to confirm urate-PecS interaction.
- Electrophoretic mobility shift assays (EMSAs) to assess urate's effect on PecS DNA binding.
- In vivo studies in Agrobacterium tumefaciens to observe gene expression changes.
Main Results:
- Four key residues involved in urate binding and conformational changes in HucR are conserved in PecS homologs.
- Agrobacterium tumefaciens PecS specifically binds urate in vitro.
- Urate binding significantly attenuates PecS binding to its operator DNA sites.
- Urate-induced dissociation of PecS from DNA leads to the transcription of pecS and pecM genes in vivo.
Conclusions:
- Urate is identified as the natural ligand for PecS.
- Urate binding to PecS regulates gene expression by reducing DNA binding affinity.
- This mechanism suggests a novel role for urate in signaling bacterial colonization of host plants.
Related Concept Videos
02:23Master Transcription Regulators
01:58Cell Specific Gene Expression
01:31Regulation of the Unfolded Protein Response
01:37The Unfolded Protein Response
02:04Co-activators and Co-repressors
02:04Covalently Linked Protein Regulators
These groups modify specific amino acids in a protein.