1M08

Crystal structure of the unbound nuclease domain of ColE7

1M08 の概要

• エントリーDOI: 10.2210/pdb1m08/pdb
• 関連するPDBエントリー: 1CEI 7CEI
• 分子名称: Colicin E7, ZINC ION, PHOSPHATE ION, ... (4 entities in total)
• 機能のキーワード: hnh motif, endonuclease, colicin, zn-binding protein, hydrolase
• 由来する生物種: Escherichia coli str. K12 substr.
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 30449.00

構造登録者

Cheng, Y.S.,Hsia, K.C.,Doudeva, L.G.,Chak, K.F.,Yuan, H.S. (登録日: 2002-06-12, 公開日: 2002-12-11, 最終更新日: 2023-11-08)

主引用文献

Cheng, Y.S.,Hsia, K.C.,Doudeva, L.G.,Chak, K.F.,Yuan, H.S.
The Crystal Structure of the Nuclease Domain of Colicin E7 Suggests a Mechanism for Binding to Double-stranded DNA by the H-N-H Endonucleases
J.mol.biol., 324:227-236, 2002

PubMed Abstract: The bacterial toxin ColE7 contains an H-N-H endonuclease domain (nuclease ColE7) that digests cellular DNA or RNA non-specifically in target cells, leading to cell death. In the host cell, protein Im7 forms a complex with ColE7 to inhibit its nuclease activity. Here, we present the crystal structure of the unbound nuclease ColE7 at a resolution of 2.1A. Structural comparison between the unbound and bound nuclease ColE7 in complex with Im7, suggests that Im7 is not an allosteric inhibitor that induces backbone conformational changes in nuclease ColE7, but rather one that inhibits by blocking the substrate-binding site. There were two nuclease ColE7 molecules in the P1 unit cell in crystals and they appeared as a dimer related to each other by a non-crystallographic dyad symmetry. Gel-filtration and cross-linking experiments confirmed that nuclease ColE7 indeed formed dimers in solution and that the dimeric conformation was more favored in the presence of double-stranded DNA. Structural comparison of nuclease ColE7 with the His-Cys box homing endonuclease I-PpoI further demonstrated that H-N-H motifs in dimeric nuclease ColE7 were oriented in a manner very similar to that of the betabetaalpha-fold of the active sites found in dimeric I-PpoI. A mechanism for the binding of double-stranded DNA by dimeric H-N-H nuclease ColE7 is suggested.

PubMed: 12441102
DOI: 10.1016/S0022-2836(02)01092-6

実験手法

X-RAY DIFFRACTION (2.1 Å)