Sulfur carrier protein probably involved in sulfur trafficking for oxidative dissimilatory sulfur metabolism. May be a component of a cytoplasmic sulfur relay system delivering sulfur to DsrC. Binds sulfur in the presence of sulfide in vitro. Energy metabolism; sulfur metabolism. Up-regulated under sulfur-oxidizing conditions (at mRNA level), i.e. when grown on reduced sulfur compounds such as sulfide, thiosulfate or elemental sulfur. 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.