YeeE-like bacterial SoxT proteins mediate sulfur import for oxidation and signal transduction.

Many sulfur-oxidizing prokaryotes oxidize sulfur compounds through a combination of initial extracytoplasmic and downstream cytoplasmic reactions. Facultative sulfur oxidizers adjust transcription to sulfur availability. While sulfur-oxidizing enzymes and transcriptional repressors have been extensively studied, sulfur import into the cytoplasm and how regulators sense external sulfur are poorly understood.

In the Alphaproteobacterium SoxR Serves a Sulfane Sulfur-Responsive Repressor of Sulfur Oxidation.

In organisms that use reduced sulfur compounds as alternative or additional electron donors to organic compounds, transcriptional regulation of genes for enzymes involved in sulfur oxidation is needed to adjust metabolic flux to environmental conditions. However, little is known about the sensing and response to inorganic sulfur compounds such as thiosulfate in sulfur-oxidizing bacteria. In the Alphaproteobacterium , one strategy is the use of the ArsR-SmtB-type transcriptional regulator SoxR.