scholarly journals MMOD-induced structural changes of hydroxylase in soluble methane monooxygenase

2018 ◽  
Author(s):  
Hanseong Kim ◽  
Sojin An ◽  
Yeo Reum Park ◽  
Hara Jang ◽  
Sang Ho Park ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Catalytic Activity ◽  
Structural Changes ◽  
Methane Monooxygenase ◽  
Regulatory Protein ◽  
Inhibitory Mechanism ◽  
Ambient Conditions ◽  
Soluble Methane Monooxygenase ◽  
Access Channel ◽  
Hydrocarbon Substrates

SummarySoluble methane monooxygenase in methanotrophs converts methane to methanol under ambient conditions1-3. The maximum catalytic activity of hydroxylase (MMOH) is achieved via interplay of its regulatory protein (MMOB) and reductase4-6. An additional auxiliary protein, MMOD, is believed to function as an inhibitor of the catalytic activity of MMOH; however, the mechanism of its action remains unknown7,8. Herein, we report the crystal structure of MMOH–MMOD complex fromMethylosinus sporiumstrain 5 (2.6 Å), which illustrates that two molecules of MMOD associate symmetrically with the canyon region of MMOH in a manner similar to MMOB, indicating that MMOD competes with MMOB for MMOH recognition. Further, MMOD binding disrupts the geometry of the di-iron centre and opens the substrate access channel. Notably, the electron density of 1,6-hexanediol at the substrate access channel mimics products of sMMO in hydrocarbon oxidation. The crystal structure of MMOH–MMOD unravels the inhibitory mechanism by which MMOD suppresses the MMOH catalytic activity, and reveals how hydrocarbon substrates/products access to the di-iron centre.

scholarly journals MMOD-induced structural changes of hydroxylase in soluble methane monooxygenase

2019 ◽  
Vol 5 (10) ◽  
pp. eaax0059
Author(s):  
Hanseong Kim ◽  
Sojin An ◽  
Yeo Reum Park ◽  
Hara Jang ◽  
Heeseon Yoo ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Structural Changes ◽  
Methane Monooxygenase ◽  
Regulatory Protein ◽  
Access Route ◽  
Inhibitory Mechanism ◽  
Ambient Conditions ◽  
Soluble Methane Monooxygenase ◽  
Auxiliary Protein ◽  
Binding Component

Soluble methane monooxygenase in methanotrophs converts methane to methanol under ambient conditions. The maximum catalytic activity of hydroxylase (MMOH) is achieved through the interplay of its regulatory protein (MMOB) and reductase. An additional auxiliary protein, MMOD, functions as an inhibitor of MMOH; however, its inhibitory mechanism remains unknown. Here, we report the crystal structure of the MMOH-MMOD complex from Methylosinus sporium strain 5 (2.6 Å). Its structure illustrates that MMOD associates with the canyon region of MMOH where MMOB binds. Although MMOD and MMOB recognize the same binding site, each binding component triggers different conformational changes toward MMOH, which then respectively lead to the inhibition and activation of MMOH. Particularly, MMOD binding perturbs the di-iron geometry by inducing two major MMOH conformational changes, i.e., MMOH β subunit disorganization and subsequent His147 dissociation with Fe1 coordination. Furthermore, 1,6-hexanediol, a mimic of the products of sMMO, reveals the substrate access route.

scholarly journals Structure of the soluble methane monooxygenase regulatory protein B

1999 ◽  
Vol 96 (14) ◽  
pp. 7877-7882 ◽  
Author(s):  
K. J. Walters ◽  
G. T. Gassner ◽  
S. J. Lippard ◽  
G. Wagner
Keyword(s):  
Methane Monooxygenase ◽  
Regulatory Protein ◽  
Soluble Methane Monooxygenase ◽  
Protein B

scholarly journals Crystal structure of unliganded TRAP: implications for dynamic allostery

2011 ◽  
Vol 434 (3) ◽  
pp. 427-434 ◽  
Author(s):  
Ali D. Malay ◽  
Masahiro Watanabe ◽  
Jonathan G. Heddle ◽  
Jeremy R. H. Tame
Keyword(s):  
Crystal Structure ◽  
Conformational Changes ◽  
Structural Changes ◽  
Bacillus Stearothermophilus ◽  
Rna Binding ◽  
Regulatory Protein ◽  
Protein A ◽  
Feedback System ◽  
Vibrational Modes ◽  
Specific Mrna

Allostery is vital to the function of many proteins. In some cases, rather than a direct steric effect, mutual modulation of ligand binding at spatially separated sites may be achieved through a change in protein dynamics. Thus changes in vibrational modes of the protein, rather than conformational changes, allow different ligand sites to communicate. Evidence for such an effect has been found in TRAP (trp RNA-binding attenuation protein), a regulatory protein found in species of Bacillus. TRAP is part of a feedback system to modulate expression of the trp operon, which carries genes involved in tryptophan synthesis. Negative feedback is thought to depend on binding of tryptophan-bound, but not unbound, TRAP to a specific mRNA leader sequence. We find that, contrary to expectations, at low temperatures TRAP is able to bind RNA in the absence of tryptophan, and that this effect is particularly strong in the case of Bacillus stearothermophilus TRAP. We have solved the crystal structure of this protein with no tryptophan bound, and find that much of the structure shows little deviation from the tryptophan-bound form. These data support the idea that tryptophan may exert its effect on RNA binding by TRAP through dynamic and not structural changes, and that tryptophan binding may be mimicked by low temperature.

Ordered Intermetallic Nanoparticles with High Catalytic Activity Prepared by an Electrochemically Induced Phase Transformation

2019 ◽  
Author(s):  
Du Sun ◽  
yunfei wang ◽  
Kenneth Livi ◽  
chuhong wang ◽  
ruichun luo ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Diffusion Mechanism ◽  
Reduction Reaction ◽  
Atomic Scale ◽  
High Catalytic Activity ◽  
Ambient Conditions ◽  
Magnetic Devices ◽  
Disordered Alloys ◽  
Ordered Intermetallic ◽  
Intermetallic Nanoparticles

<div> <p>The synthesis of alloys with long range atomic scale ordering (ordered intermetallics) is an emerging field of nanochemistry. Ordered intermetallic nanoparticles are useful for a wide variety of applications such as catalysis, superconductors, and magnetic devices. However, the preparation of nanostructured ordered intermetallics is challenging in comparison to disordered alloys, hindering progress in materials development. We report a process for converting colloidally synthesized ordered intermetallic PdBi<sub>2</sub> to ordered intermetallic Pd<sub>3</sub>Bi nanoparticles under ambient conditions by an electrochemically induced phase transition. The low melting point of PdBi<sub>2</sub> corresponds to low vacancy formation energies which enables the facile removal of the Bi from the surface, while simultaneously enabling interdiffusion of the constituent atoms via a vacancy diffusion mechanism under ambient conditions. The resulting phase-converted ordered intermetallic Pd<sub>3</sub>Bi exhibits 11x and 3.5x higher mass activty and high methanol tolerance for the oxygen reduction reaction compared to Pt/C and Pd/C, respectively,which is the highest reported for a Pd-based catalyst, to the best of our knowledge. These results establish a key development in the synthesis of noble metal rich ordered intermetallic phases with high catalytic activity, and sets forth guidelines for the design of ordered intermetallic compounds under ambient conditions.</p> </div>

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