Role of Selenoproteins in Bacterial Pathogenesis

Abstract

The trace element selenium is an essential micronutrient that plays an important role in maintaining homeostasis of several tissues including the immune system of mammals. The vast majority of the biological functions of selenium are mediated via selenoproteins, proteins which incorporate the selenium-containing amino acid selenocysteine. Several bacterial infections of humans and animals are associated with decreased levels of selenium in the blood and an adjunct therapy with selenium often leads to favorable outcomes. Many pathogenic bacteria are also capable of synthesizing selenocysteine suggesting that selenoproteins may have a role in bacterial physiology. Interestingly, the composition of host microbiota is also regulated by dietary selenium levels. Therefore, bacterial pathogens, microbiome, and host immune cells may be competing for a limited supply of selenium. Elucidating how selenium, in particular selenoproteins, may regulate pathogen virulence, microbiome diversity, and host immune response during a bacterial infection is critical for clinical management of infectious diseases.

Keywords: Bacteria; Immune Response; Microbiota; Pathogen; Selenium; Selenoproteins.

Figure 1.. Schematic representing the close interactions of a pathogen, microbiome and immune cells in the context of requirement for selenium.

Several bacterial pathogens require selenium for adapting to host environment, particularly to the anaerobic environment. Host microbiome also requires selenium as selenium depletion leads to dysbiosis of microbiota. Host immune cells also require selenium for their optimum functions.

Figure 2.. Involvement of selenium and selenoproteins in host-bacteria interactions. Several immune functions are dependent or modulated by selenoproteins.

Similarly, selenoproteins also contribute to the pathogen fitness in host environment. The dynamic interaction and consequent pathogenesis is thus regulated in part by the limited selenium availability.