4XZ6

TmoX in complex with TMAO

4XZ6 の概要

• エントリーDOI: 10.2210/pdb4xz6/pdb
• 分子名称: Glycine betaine/proline ABC transporter, periplasmic substrate-binding protein, trimethylamine oxide, CALCIUM ION, ... (6 entities in total)
• 機能のキーワード: abc transporter, substrate binding protein, complex, transport protein
• 由来する生物種: Ruegeria pomeroyi (strain ATCC 700808 / DSM 15171 / DSS-3)
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 75206.20

構造登録者

Zhang, Y.Z.,Li, C.Y. (登録日: 2015-02-04, 公開日: 2015-08-19, 最終更新日: 2024-10-23)

主引用文献

Li, C.Y.,Chen, X.L.,Shao, X.,Wei, T.D.,Wang, P.,Xie, B.B.,Qin, Q.L.,Zhang, X.Y.,Su, H.N.,Song, X.Y.,Shi, M.,Zhou, B.C.,Zhang, Y.Z.
Mechanistic Insight into Trimethylamine N-Oxide Recognition by the Marine Bacterium Ruegeria pomeroyi DSS-3
J.Bacteriol., 197:3378-3387, 2015

PubMed Abstract: Trimethylamine N-oxide (TMAO) is an important nitrogen source for marine bacteria. TMAO can also be metabolized by marine bacteria into volatile methylated amines, the precursors of the greenhouse gas nitrous oxide. However, it was not known how TMAO is recognized and imported by bacteria. Ruegeria pomeroyi DSS-3, a marine Roseobacter, has an ATP-binding cassette transporter, TmoXWV, specific for TMAO. TmoX is the substrate-binding protein of the TmoXWV transporter. In this study, the substrate specificity of TmoX of R. pomeroyi DSS-3 was characterized. We further determined the structure of the TmoX/TMAO complex and studied the TMAO-binding mechanism of TmoX by biochemical, structural, and mutational analyses. A Ca(2+) ion chelated by an extended loop in TmoX was shown to be important for maintaining the stability of TmoX. Molecular dynamics simulations indicate that TmoX can alternate between "open" and "closed" states for binding TMAO. In the substrate-binding pocket, four tryptophan residues interact with the quaternary amine of TMAO by cation-π interactions, and Glu131 forms a hydrogen bond with the polar oxygen atom of TMAO. The π-π stacking interactions between the side chains of Phe and Trp are also essential for TMAO binding. Sequence analysis suggests that the TMAO-binding mechanism of TmoX may have universal significance in marine bacteria, especially in the marine Roseobacter clade. This study sheds light on how marine microorganisms utilize TMAO.

PubMed: 26283766
DOI: 10.1128/JB.00542-15

実験手法

X-RAY DIFFRACTION (2.2 Å)