5IPY image
Entry Detail
PDB ID:
5IPY
Keywords:
Title:
Crystal structure of WT RnTmm
Biological Source:
PDB Version:
Deposition Date:
2016-03-10
Release Date:
2017-01-18
Method Details:
Experimental Method:
Resolution:
1.50 Å
R-Value Free:
0.16
R-Value Work:
0.14
R-Value Observed:
0.14
Space Group:
P 1 21 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Flavin-containing monooxygenase
Mutations:E153A, D154A
Chain IDs:A, B
Chain Length:453
Number of Molecules:2
Biological Source:Roseovarius nubinhibens (strain ATCC BAA-591 / DSM 15170 / ISM)
Primary Citation
Structural mechanism for bacterial oxidation of oceanic trimethylamine into trimethylamine N-oxide
Mol. Microbiol. 103 992 1003 (2017)
PMID: 27997715 DOI: 10.1111/mmi.13605

Abstact

Trimethylamine (TMA) and trimethylamine N-oxide (TMAO) are widespread in the ocean and are important nitrogen source for bacteria. TMA monooxygenase (Tmm), a bacterial flavin-containing monooxygenase (FMO), is found widespread in marine bacteria and is responsible for converting TMA to TMAO. However, the molecular mechanism of TMA oxygenation by Tmm has not been explained. Here, we determined the crystal structures of two reaction intermediates of a marine bacterial Tmm (RnTmm) and elucidated the catalytic mechanism of TMA oxidation by RnTmm. The catalytic process of Tmm consists of a reductive half-reaction and an oxidative half-reaction. In the reductive half-reaction, FAD is reduced and a C4a-hydroperoxyflavin intermediate forms. In the oxidative half-reaction, this intermediate attracts TMA through electronic interactions. After TMA binding, NADP+ bends and interacts with D317, shutting off the entrance to create a protected micro-environment for catalysis and exposing C4a-hydroperoxyflavin to TMA for oxidation. Sequence analysis suggests that the proposed catalytic mechanism is common for bacterial Tmms. These findings reveal the catalytic process of TMA oxidation by marine bacterial Tmm and first show that NADP+ undergoes a conformational change in the oxidative half-reaction of FMOs.

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