1XMF

Structure of Mn(II)-Soaked Apo Methane Monooxygenase Hydroxylase Crystals from M. capsulatus (Bath)

1XMF の概要

• エントリーDOI: 10.2210/pdb1xmf/pdb
• 関連するPDBエントリー: 1XMG 1XMH
• 分子名称: Methane monooxygenase component A alpha chain, Methane monooxygenase component A beta chain, Methane monooxygenase component A gamma chain, ... (6 entities in total)
• 機能のキーワード: dimanganese; mmoh; diiron; methane; four-helix bundle, oxidoreductase
• 由来する生物種: Methylococcus capsulatus; 詳細
• タンパク質・核酸の鎖数: 6
• 化学式量合計: 251538.37

構造登録者

Sazinsky, M.H.,Merkx, M.,Cadieux, E.,Tang, S.,Lippard, S.J. (登録日: 2004-10-02, 公開日: 2005-01-18, 最終更新日: 2023-08-23)

主引用文献

Sazinsky, M.H.,Merkx, M.,Cadieux, E.,Tang, S.,Lippard, S.J.
Preparation and X-ray Structures of Metal-Free, Dicobalt and Dimanganese Forms of Soluble Methane Monooxygenase Hydroxylase from Methylococcus capsulatus (Bath)
Biochemistry, 43:16263-16276, 2004

PubMed Abstract: A three-component soluble methane monooxygenase (sMMO) enzyme system catalyzes the hydroxylation of methane to methanol at a carboxylate-bridged diiron center housed in the alpha-subunit of the hydroxylase (MMOH). Catalysis is facilitated by the presence of a regulatory protein (MMOB) and inhibited by MMOD, a protein of unknown function encoded in the sMMO operon. Both MMOB and MMOD are presumed to bind to the same region of the MMOH alpha-subunit. A colorimetric method for monitoring removal of Fe(II) from MMOH was developed using 1,10-phenanthroline and yields apo MMOH with <0.1 Fe/homodimer. With the use of this method, it was possible to investigate the X-ray structure of the apoenzyme and to perform metal reconstitution studies. Using MMOH from Methylococccus capsulatus (Bath), the effects of MMOB and MMOD on metal binding were studied and structural perturbations relevant to the function of this enzyme were identified. X-ray crystal structures of the apo, Mn(II)-soaked, and Co(II)-grown MMOH, determined to 2.3 A or greater resolution, reveal that the presence of metal ions is essential for the proper folding of helices E, F, and H of the alpha-subunit. The active sites of Mn(II)-soaked and Co(II)-grown MMOH are similar to that of reduced, native MMOH with notable differences in the metal-metal distances and ligand coordination sphere that may reflect how this dinuclear metal center might change in the presence of MMOB. MMOB and MMOD decrease the rate of removal of Fe(II) from the enzyme by 22- and 16-fold, respectively. On the basis of previous studies, it is hypothesized that MMOB, and perhaps MMOD, function to block solvent access to the MMOH active site. Finally, ITC studies and the observed disorder in helices E, F, and H in the apo and Mn(II)-soaked structures suggest that these regions of MMOH are critical for MMOB and MMOD binding.

PubMed: 15610020
DOI: 10.1021/bi048140z

実験手法

X-RAY DIFFRACTION (2.32 Å)