2QQA

Crystal Structure of DtxR(E9A C102D) Complexed with Nickel(II)

2QQA の概要

• エントリーDOI: 10.2210/pdb2qqa/pdb
• 関連するPDBエントリー: 1DDN 1P92 1XCV 2QQ9 2QQB 2TDX
• 分子名称: Diphtheria toxin repressor, NICKEL (II) ION, PHOSPHATE ION, ... (4 entities in total)
• 機能のキーワード: repressor, regulator, dtxr, helix-turn-helix, metal ion, activation, dna-binding, ferrous iron, cytoplasm, transcription, transcription regulation, transcription regulator
• 由来する生物種: Corynebacterium diphtheriae
• 細胞内の位置: Cytoplasm: P33120
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 25516.06

構造登録者

D'Aquino, J.A.,Lattimer, J.R.,Denninger, A.,D'Aquino, K.E.,Ringe, D. (登録日: 2007-07-26, 公開日: 2007-10-30, 最終更新日: 2023-08-30)

主引用文献

D'Aquino, J.A.,Lattimer, J.R.,Denninger, A.,D'Aquino, K.E.,Ringe, D.
Role of the N-Terminal Helix in the Metal Ion-Induced Activation of the Diphtheria Toxin Repressor DtxR.
Biochemistry, 46:11761-11770, 2007

PubMed Abstract: The metal ion-regulated transcriptional repressor DtxR has been shown to repress the transcription of the diphtheria toxin and other genes associated with ferrous ion homeostasis in Corynebacterium diphtheriae. In vivo studies of single-alanine mutations located in the N-terminal helix of DtxR show that the activity of the mutants is reduced compared to that of the wild type. The three-dimensional structures of the apo and activated forms of DtxR show conformational changes in the N-terminal helix resulting from metal ion activation. We have studied the N-terminal helix mutants DtxR(D6A,C102D), DtxR(E9A,C102D), and DtxR(M10A,C102D) using crystallographic and calorimetric techniques to gain insight into the possible reasons for such behavior at a molecular level. The binding affinities for metal ion extracted from the calorimetric titrations of the mutants DtxR(D6A,C102D) and DtxR(E9A,C102D) are very similar to those found for DtxR(C102D), while the same experiments performed with the mutant DtxR(M10A,C102D), bearing the M10A mutation located in binding site 2, show a decreased binding affinity in a predictable fashion. These results suggest that the decreased activity observed in these mutants cannot be explained exclusively by changes in the binding affinity of the repressor. The crystal structures of Ni-DtxR(M10A,C102D), Ni-DtxR(E9A,C102D), and Ni-DtxR(D6A,C102D) clearly show the presence of two metal ions bound. In the structure of Ni-DtxR(M10A,C102D), a water replaces Met10 in binding site 2. In the structure of Ni-DtxR(D6A,C102D), the nonhelical conformation of the N-terminal region characteristic of the activated form is absent. The side chain of Asp6 is critical in stabilization of the nonhelical conformation. This conformation is identical in all high-resolution structures of activated DtxR with an intact N-terminal helix, suggesting relevance in DtxR's regulatory function.

PubMed: 17902703
DOI: 10.1021/bi7007883

実験手法

X-RAY DIFFRACTION (2.1 Å)