The inner workings of the hydrazine synthase multiprotein complex

Area of Science:

• Biochemistry
• Microbiology
• Environmental Science

Background:

• Anaerobic ammonium oxidation (anammox) is crucial for the nitrogen cycle and wastewater treatment.
• The anammox process utilizes hydrazine, a reactive intermediate, but its synthesis mechanism was unknown.
• Hydrazine is also known for its use as a rocket fuel due to its high reducing power.

Purpose of the Study:

• To elucidate the enzymatic mechanism of biological hydrazine synthesis.
• To determine the structure of the hydrazine synthase complex from Kuenenia stuttgartiensis.

Main Methods:

• X-ray crystallography at 2.7 Å resolution.
• Biophysical and spectroscopic studies.
• Isolation of the hydrazine synthase multiprotein complex.

Main Results:

• The crystal structure of the hydrazine synthase complex was determined.
• The complex is an elongated dimer of heterotrimers with unique active sites and internal tunnels.
• A two-step mechanism for hydrazine synthesis involving nitric oxide reduction and ammonia condensation was proposed.

Conclusions:

• This study provides the first structural insights into biological hydrazine synthesis.
• Understanding this mechanism is vital for comprehending nitrogen conversion in nature.
• The findings have implications for optimizing anammox-based wastewater treatment.