ジャーナル: FEBS J / 年: 2025 タイトル: Bacterial transcriptional repressor NrdR - a flexible multifactorial nucleotide sensor. 著者: Inna Rozman Grinberg / Ornella Bimaï / Saher Shahid / Lena Philipp / Markel Martínez-Carranza / Ipsita Banerjee / Daniel Lundin / Pål Stenmark / Britt-Marie Sjöberg / Derek T Logan / 要旨: NrdR is a bacterial transcriptional repressor consisting of a zinc (Zn)-ribbon domain followed by an ATP-cone domain. Understanding its mechanism of action could aid the design of novel ...NrdR is a bacterial transcriptional repressor consisting of a zinc (Zn)-ribbon domain followed by an ATP-cone domain. Understanding its mechanism of action could aid the design of novel antibacterials. NrdR binds specifically to two "NrdR boxes" upstream of ribonucleotide reductase operons, of which Escherichia coli has three: nrdHIEF, nrdDG and nrdAB, in the last of which we identified a new box. We show that E. coli NrdR (EcoNrdR) has similar binding strength to all three sites when loaded with ATP plus deoxyadenosine triphosphate (dATP) or equivalent diphosphate combinations. No other combination of adenine nucleotides promotes binding to DNA. We present crystal structures of EcoNrdR-ATP-dATP and EcoNrdR-ADP-dATP, which are the first high-resolution crystal structures of an NrdR. We have also determined cryo-electron microscopy structures of DNA-bound EcoNrdR-ATP-dATP and novel filaments of EcoNrdR-ATP. Tetrameric forms of EcoNrdR involve alternating interactions between pairs of Zn-ribbon domains and ATP-cones. The structures reveal considerable flexibility in relative orientation of ATP-cones vs Zn-ribbon domains. The structure of DNA-bound EcoNrdR-ATP-dATP shows that significant conformational rearrangements between ATP-cones and Zn-ribbons accompany DNA binding while the ATP-cones retain the same relative orientation. In contrast, ATP-loaded EcoNrdR filaments show rearrangements of the ATP-cone pairs and sequester the DNA-binding residues of NrdR such that they are unable to bind to DNA. Our results, in combination with a previous structural and biochemical study, point to highly flexible EcoNrdR structures that, when loaded with the correct nucleotides, adapt to an optimal promoter-binding conformation.
名称: E. coli NrdR/ATP/dATP/DNA / タイプ: complex / ID: 1 / 親要素: 0 / 含まれる分子: all 詳細: Tetrameric transcription factor NrdR from E. coli in complex with ATP, dATP and a DNA 57-mer containing two NrdR boxes.
chain_id: F, source_name: PDB, initial_model_type: experimental model
詳細
Three models were used to fit the best cryo-EM volume: DNA from the S. coelicor NrdR-dATP-ATP-DNA complex, and pairs of ATP-cones and Zn-ribbons from the EcNrdR-ATP-dAMPPNP complex. These were fitted to the volume using Molrep in the order DNA:ATP-cones:Zn ribbons. Domain-wise rigid body real space refinement was then carried out using phenix.refine.