Alternative oxidase in bacteria

While alternative oxidase (AOX) was discovered in bacteria in 2003, the expression, function, and evolutionary history of this protein in these important organisms is largely unexplored. To date, expression and functional analysis is limited to studies in the Proteobacteria Novosphingobium aromaticivorans and Vibrio fischeri, where AOX likely plays roles in maintenance of cellular energy homeostasis and supporting responses to cellular stress. This review describes the history of the study of AOX in bacteria, details current knowledge of the predicted biochemical and structural characteristics, distribution, and function of bacterial AOX, and highlights interesting areas for the future study of AOX in bacteria. •Alternative oxidase (AOX) has a broad, yet uneven, distribution in bacteria•The physiological function, expression patterns, and evolutionary history of bacterial AOX are largely unexplored•Furthering the study of bacterial AOX can provide insight into bacterial physiology and its connection to ecosystem processes