The response to thiosulfate availability in Hyphomicrobium denitrificans

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. Addressing this gap, we show that SoxT1A and SoxT1B, which resemble YeeE/YedE-family thiosulfate transporters and are encoded alongside sulfur oxidation and transcriptional regulation genes, fulfill these roles in the Alphaproteobacterium Hyphomicrobium denitrificans. RT-qPCR provided initial evidence that SoxT1A and SoxT1B from H. denitrificans may be intricate components of the oxidation pathway and/or involved in its transcriptional regulation. Here, we extend these analyses with genome-wide mRNA-Seq data for the reference strain, comparing transcription in the absence and presence of 2 mM thiosulfate Overall design: To investigate the response of the chemoorganotrophic bacterium Hyphomicrobium denitrificans to the availability of thiosulfate as an additional electron donor, the delta tsdA reference strain, which lacks the tetrathionate-forming enzyme thiosulfate dehydrogenase was grown under two different conditions. Cells were grown on methanol under aerobic conditions either in the absence or in the additional presence of thiosulfate.