Exploring the Biological Sulfur-Oxidation Cycle Using Genetic Engineering

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Vageesha Herath
Annetta Rowe


By Vageesha Herath, Biochemistry

Advisor: Annetta Rowe

Presentation ID: 179

Abstract: Sulfur is an abundant non-metal found in the universe and plays an important role as a structural element, carbon carrier, and redox center. Microbial activity has a major impact on sulfur cycling globally, yet the biochemistry of many solid phase sulfur minerals remain somewhat elusive. The marine bacterium Thioclava electrotropha ElOx9 is known for its sulfur oxidation ability, via the Sox pathway The Sox pathway, is found in a variety of microbes and encodes for proteins involved in thiosulfate oxidation. These proteins are largely periplasmic and how electrons from extracellular and/or mineral sulfur species remains uncharacterized. The project examines the role of genes Sox C and Sox D within the Sox pathway and its potential role in extracellular sulfur oxidation. Sox(CD) is a periplasmic multiprotein enzyme complex comprised of two molybdoproteins (SoxC) and two diheme c-type cytochromes (SoxD). To understand the functions of these genes, a mutant strain of Thioclava was created where the Sox C and Sox D genes were deleted. The SoxCD knockout strain will be evaluated for the ability to oxidize inorganic sulfur compounds by plating mutant strains on agar plates containing thiosulphate or extracellular solid phase sulfur. The above methodology will provide insights into the function of SoxCD will regard to thiosulfate oxidation (diffusible to the periplasm) and extracellular sulfur. Continued experimentation will focus on the potential role of SoxCD in extracellular electron transfer with an electrode. Understanding the mechanism behind inorganic sulfur oxidation in Thioclava will help researchers to understand the extracellular electron transfer mechanisms.

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Category: New Frontiers