Se-ing bacteria in a new light: investigating selenium metabolism in Bacillus selenitireducens MLS10

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Michael Banner Wells (Creator)
The University of North Carolina at Greensboro (UNCG )
Web Site:
Malcolm Schug

Abstract: Prokaryotes metabolize selenium in two significant ways. One way prokaryotes metabolize selenium is through incorporation into the 21st amino acid selenocysteine (Sec), which is inserted into proteins co-translationally. Additionally, many prokaryotes exploit the selenium oxyanions selenite and selenate as terminal electron acceptors in anaerobic respiration. Little is known about the evolution of selenoproteins in prokaryotes. While selenate respiration has been studied in several bacteria, nothing is known about the physiology of selenite respiration. I investigated both aspects of selenium metabolism in Bacillus selenitireducens MLS10 by annotating the selenoproteome of MLS10 and constructing phylogenies of these selenoproteins to investigate the evolution of selenoproteins in the bacilli, and by obtaining the protein profiles using SDS-PAGE, determined the cytochrome content using the pyridine hemochrome assay, and tested for enzyme activity in native gels using selenite-grown MLS10 cells. My research demonstrates that the bacilli exploit Sec residues to a far greater extent than has heretofore been appreciated, that the selenoproteins exploited by the bacilli are closely related to those of the clostridia, and provides evidence that the evolution of selenoproteins in Gram-positive bacteria and the d-Proteobacteria is characterized by extensive horizontal gene transfer. Finally, my research provides evidence that selenite respiration is a distinct, inducible respiratory pathway in MLS10, and suggests future directions for further testing of this hypothesis.

Additional Information

Language: English
Date: 2015
Respiration, Selenite, Selenoproteins
Selenium $x Metabolism
Selenium $x Physiological effect

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