7NMB

cytoplasmic domain of Vibrio cholerae ToxR

Summary for 7NMB

• Entry DOI: 10.2210/pdb7nmb/pdb
• NMR Information: BMRB: 34606
• Descriptor: Cholera toxin transcriptional activator (1 entity in total)
• Functional Keywords: dna binding domain whth transcription factor, transcription
• Biological source: Vibrio cholerae
• Total number of polymer chains: 1
• Total formula weight: 16641.77

Authors

Gubensaek, N.,Zangger, K.,Hartlmueller, C.,Madl, T. (deposition date: 2021-02-23, release date: 2021-10-20, Last modification date: 2024-06-19)

Primary citation

Gubensak, N.,Schrank, E.,Hartlmuller, C.,Gobl, C.,Falsone, F.S.,Becker, W.,Wagner, G.E.,Pulido, S.,Meyer, N.H.,Pavkov-Keller, T.,Madl, T.,Reidl, J.,Zangger, K.
Structural and DNA-binding properties of the cytoplasmic domain of Vibrio cholerae transcription factor ToxR.
J.Biol.Chem., 297:101167-101167, 2021

PubMed Abstract: ToxR represents an essential transcription factor of Vibrio cholerae, which is involved in the regulation of multiple, mainly virulence associated genes. Its versatile functionality as activator, repressor or coactivator suggests a complex regulatory mechanism, whose clarification is essential for a better understanding of the virulence expression system of V. cholerae. Here, we provide structural information elucidating the organization and binding behavior of the cytoplasmic DNA-binding domain of ToxR (cToxR), containing a winged helix-turn-helix (wHTH) motif. Our analysis reveals unexpected structural features of this domain expanding our knowledge of a poorly defined subfamily of wHTH proteins. cToxR forms an extraordinary long α-loop and furthermore has an additional C-terminal beta strand, contacting the N-terminus and thus leading to a compact fold. The identification of the exact interactions between ToxR and DNA contributes to a deeper understanding of this regulatory process. Our findings not only show general binding of the soluble cytoplasmic domain of ToxR to DNA, but also indicate a higher affinity for the toxT motif. These results support the current theory of ToxR being a "DNA-catcher" to enable binding of the transcription factor TcpP and thus activation of virulence-associated toxT transcription. Although, TcpP and ToxR interaction is assumed to be crucial in the activation of the toxT genes, we could not detect an interaction event of their isolated cytoplasmic domains. We therefore conclude that other factors are needed to establish this protein-protein interaction, e.g., membrane attachment, the presence of their full-length proteins and/or other intermediary proteins that may facilitate binding.

PubMed: 34487759
DOI: 10.1016/j.jbc.2021.101167

Experimental method

SOLUTION NMR