9HH1

LysR Type Transcriptional Regulator LsrB from Agrobacterium tumefaciens

Summary for 9HH1

• Entry DOI: 10.2210/pdb9hh1/pdb
• EMDB information: 52168
• Descriptor: Transcriptional regulator, LysR family (1 entity in total)
• Functional Keywords: lysr-type trancriptional regulator, dna-binding, agrobacterium, transcription factor, dna binding protein
• Biological source: Agrobacterium fabrum str. C58
• Total number of polymer chains: 2
• Total formula weight: 70748.62

Authors

Elders, H.,Schmidt, J.J.,Fiedler, R.,Hofmann, E.,Narberhaus, F. (deposition date: 2024-11-20, release date: 2025-04-16)

Primary citation

Schmidt, J.J.,Brandenburg, V.B.,Elders, H.,Shahzad, S.,Schakermann, S.,Fiedler, R.,Knoke, L.R.,Pfander, Y.,Dietze, P.,Bille, H.,Gartner, B.,Albin, L.J.,Leichert, L.I.,Bandow, J.E.,Hofmann, E.,Narberhaus, F.
Two redox-responsive LysR-type transcription factors control the oxidative stress response of Agrobacterium tumefaciens.
Nucleic Acids Res., 53:-, 2025

PubMed Abstract: Pathogenic bacteria often encounter fluctuating reactive oxygen species (ROS) levels, particularly during host infection, necessitating robust redox-sensing mechanisms for survival. The LysR-type transcriptional regulator (LTTR) OxyR is a widely conserved bacterial thiol-based redox sensor. However, members of the Rhizobiales also encode LsrB, a second LTTR with potential redox-sensing function. This study explores the roles of OxyR and LsrB in the plant-pathogen Agrobacterium tumefaciens. Through single and combined deletions, we observed increased H2O2 sensitivity, underscoring their function in oxidative defense. Genome-wide transcriptome profiling under H2O2 exposure revealed that OxyR and LsrB co-regulate key antioxidant genes, including katG, encoding a bifunctional catalase/peroxidase. Agrobacterium tumefaciens LsrB possesses four cysteine residues potentially involved in redox sensing. To elucidate the structural basis for redox-sensing, we applied single-particle cryo-EM (cryogenic electron microscopy) to experimentally confirm an AlphaFold model of LsrB, identifying two proximal cysteine pairs. In vitro thiol-trapping coupled with mass spectrometry confirmed reversible thiol modifications of all four residues, suggesting a functional role in redox regulation. Collectively, these findings reveal that A. tumefaciens employs two cysteine-based redox sensing transcription factors, OxyR and LsrB, to withstand oxidative stress encountered in host and soil environments.

PubMed: 40193708
DOI: 10.1093/nar/gkaf267

Experimental method

ELECTRON MICROSCOPY (3.9 Å)