The physiology and evolution of microbial selenium metabolism

Area of Science:

• Biochemistry
• Microbiology
• Evolutionary Biology

Background:

• Selenium is an essential trace element crucial for life across all domains.
• Phylogenetic evidence suggests early metabolism of selenium for synthesizing selenocysteine.
• Selenium metabolism is fundamental to both environmental processes and primordial life adaptations.

Purpose of the Study:

• To provide a comprehensive review of selenium metabolism in bacteria and archaea.
• To highlight the physiology and evolution of both assimilatory and dissimilatory selenium metabolism.
• To discuss mechanisms of selenium respiration and its role in the global selenium biogeochemical cycle.

Main Methods:

• Review of existing literature on selenium metabolism.
• Analysis of phylogenetic evidence for early selenium utilization.
• Discussion of structural biology findings on selenocysteine incorporation.
• Examination of selenium's role in tRNA and enzyme cofactors.

Main Results:

• Selenium metabolism involves reductive transformations for macromolecule assimilation and anaerobic respiration.
• Selenocysteine synthesis and incorporation into proteins are key processes in bacteria.
• Selenium is incorporated into tRNA and acts as a cofactor in molybdenum hydroxylase enzymes.
• Conserved and derived mechanisms of selenium metabolism exist in bacteria and archaea.

Conclusions:

• Selenium metabolism is a conserved, ancient process essential for diverse biological functions.
• Understanding selenium metabolism provides insights into early life evolution and the global selenium cycle.
• This review consolidates knowledge on selenium's physiological and evolutionary significance in microorganisms.