Sulfur carrier protein involved in sulfur trafficking for oxidative dissimilatory sulfur metabolism. Component of a sulfur relay system that starts with the sulfur-mobilizing rhodanese-like protein Rhd_2599 (Alvin_2599), which transfers the sulfur from a low-molecular-weight thiol, maybe glutathione, to the TusA protein (Alvin_2600); TusA serves as the sulfur donor for DsrEFH, which persulfurates DsrC; persulfurated DsrC very probably serves as a direct substrate for reverse-acting sulfite reductase, DsrAB. TusA seems to be not exclusively dedicated to sulfur oxidation and may have other important roles in the cell. Might also act as a sulfur mediator required for 2-thiouridine formation of tRNA. Energy metabolism; sulfur metabolism. Mostly a monomer, a small portion forms homodimer via intermolecular disulfide bonds. Tightly interacts with DsrEFH. Up-regulated under sulfur-oxidizing conditions (at mRNA level), i.e. when grown on reduced sulfur compounds such as sulfide, thiosulfate or elemental sulfur (PubMed:24648525). TusA is one of the major proteins in A.vinosum cells grown on malate or on reduced sulfur compounds (PubMed:24487535). A mutant strain lacking rhd_2599, tusA and dsrE2, although not viable in liquid culture, is clearly sulfur oxidation negative upon growth on solid media containing sulfide, and shows massive accumulation of intercellular sulfur globules. Belongs to the sulfur carrier protein TusA family.