Structure-function relationships of anaerobic gas-processing metalloenzymes

Area of Science:

• Biochemistry and Astrobiology
• Origin of Life Research

Background:

• Reactions involving gases such as hydrogen (H2), nitrogen (N2), carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) are hypothesized to be fundamental to the origin of life.
• The active-site structures of enzymes involved in these reactions often exhibit similarities to mineral structures, suggesting a link between geochemistry and early biochemistry.

Purpose of the Study:

• To elucidate plausible mechanisms for gas-based metabolism in extant microorganisms.
• To investigate the role of enzyme active sites and protein matrices in facilitating early metabolic pathways.

Main Methods:

• Integration of protein crystallography to determine enzyme structures.
• Application of various spectroscopic techniques to study reaction intermediates and dynamics.
• Utilisation of theoretical calculations and model chemistry to simulate reaction mechanisms.

Main Results:

• Plausible mechanisms for gas-based metabolism have been proposed.
• Enzyme active sites, centered on metal ions, are shown to be critical for these reactions.
• The protein matrix plays a regulatory role in controlling reactivity and transport of substrates and products.

Conclusions:

• Gas-based metabolic reactions, facilitated by mineral-like enzyme active sites, were likely central to the origin of life.
• The protein environment precisely regulates the function of metal centers, enabling efficient substrate and product trafficking via internal pathways, specific ligation, and dielectric effects.