Complementary functioning of the component proteins of nitrogenase from several bacteria

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Nitrogenase is a complex enzyme essential for biological nitrogen fixation.
• Understanding the interaction of nitrogenase components from different species is crucial for bioengineering efforts.

Purpose of the Study:

• To investigate the cross-reactivity of nitrogenase proteins (MoFe and Fe components) from eight different organisms.
• To determine the extent of functional compatibility between homologous and heterologous nitrogenase components.

Main Methods:

• Purification of nitrogenase proteins from eight distinct organisms.
• Systematic cross-reactivity assays involving 64 possible combinations of MoFe and Fe proteins.
• Assays for acetylene reduction, ammonia formation, hydrogen evolution, and ATP hydrolysis.

Main Results:

• 45 out of 56 heterologous crosses yielded active hybrid nitrogenases, indicating broad functional compatibility.
• Several crosses showed unusual dependencies on pH, component ratio, and protein concentration.
• Some heterologous combinations formed inactive but tight-binding complexes, and others showed unique ATP hydrolysis activity.

Conclusions:

• Nitrogenase components exhibit significant cross-reactivity across a wide range of organisms.
• Hybrid nitrogenases can be generated, offering potential for novel enzyme engineering.
• The functional activity of hybrid nitrogenases is influenced by environmental factors similar to homologous enzymes.