1S56

Crystal Structure of "Truncated" Hemoglobin N (HbN) from Mycobacterium tuberculosis, Soaked with Xe Atoms

1S56 の概要

• エントリーDOI: 10.2210/pdb1s56/pdb
• 関連するPDBエントリー: 1IDR 1RTE
• 分子名称: Hemoglobin-like protein HbN, CYANIDE ION, POTASSIUM ION, ... (8 entities in total)
• 機能のキーワード: group i truncated hemoglobin, oxygen storage-transport complex, oxygen storage/transport
• 由来する生物種: Mycobacterium tuberculosis
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 31400.47

構造登録者

Milani, M.,Pesce, A.,Ouellet, Y.,Dewilde, S.,Friedman, J.,Ascenzi, P.,Guertin, M.,Bolognesi, M. (登録日: 2004-01-20, 公開日: 2004-06-29, 最終更新日: 2023-08-23)

主引用文献

Milani, M.,Pesce, A.,Ouellet, Y.,Dewilde, S.,Friedman, J.,Ascenzi, P.,Guertin, M.,Bolognesi, M.
Heme-ligand tunneling in group I truncated hemoglobins
J.Biol.Chem., 279:21520-21525, 2004

PubMed Abstract: Truncated hemoglobins (trHbs) are small hemoproteins forming a separate cluster within the hemoglobin superfamily; their functional roles in bacteria, plants, and unicellular eukaryotes are marginally understood. Crystallographic investigations have shown that the trHb fold (a two-on-two alpha-helical sandwich related to the globin fold) hosts a protein matrix tunnel system offering a potential path for ligand diffusion to the heme distal site. The tunnel topology is conserved in group I trHbs, although with modulation of its size/structure. Here, we present a crystallographic investigation on trHbs from Mycobacterium tuberculosis, Chlamydomonas eugametos, and Paramecium caudatum, showing that treatment of trHb crystals under xenon pressure leads to binding of xenon atoms at specific (conserved) sites along the protein matrix tunnel. The crystallographic results are in keeping with data from molecular dynamics simulations, where a dioxygen molecule is left free to diffuse within the protein matrix. Modulation of xenon binding over four main sites is related to the structural properties of the tunnel system in the three trHbs and may be connected to their functional roles. In a parallel crystallographic investigation on M. tuberculosis trHbN, we show that butyl isocyanide also binds within the apolar tunnel, in excellent agreement with concepts derived from the xenon binding experiments. These results, together with recent data on atypical CO rebinding kinetics to group I trHbs, underline the potential role of the tunnel system in supporting diffusion, but also accumulation in multiple copies, of low polarity ligands/molecules within group I trHbs.

PubMed: 15016811
DOI: 10.1074/jbc.M401320200

実験手法

X-RAY DIFFRACTION (2.43 Å)