Institut für Mikrobiologie & Biotechnologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany.
Institute for Integrated Natural Sciences, University of Koblenz, Koblenz, Germany.
Commun Biol. 2024 Nov 21;7(1):1548. doi: 10.1038/s42003-024-07270-7.
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. SoxT1A mutants are sulfur oxidation-negative despite high transcription levels of sulfur oxidation genes, showing that SoxT1A delivers sulfur to the cytoplasm for its further oxidation. SoxT1B serves as a signal transduction unit for the transcriptional repressor SoxR, as SoxT1B mutants are sulfur oxidation-negative due to low transcription unless SoxR is also absent. Thus, SoxT1A and SoxT1B play essential but distinct roles in oxidative sulfur metabolism and its regulation.
许多硫氧化原核生物通过胞外初始反应和下游胞质反应的结合来氧化硫化合物。兼性硫氧化菌会根据硫的可用性来调整转录。虽然硫氧化酶和转录抑制剂已得到广泛研究，但硫向细胞质的导入以及调节剂如何感知外部硫的情况仍知之甚少。为了解决这一差距，我们表明，类似于 YeeE/YedE 家族硫代硫酸盐转运蛋白的 SoxT1A 和 SoxT1B 与硫氧化和转录调控基因一起编码，在 Alphaproteobacterium Hyphomicrobium denitrificans 中发挥这些作用。尽管硫氧化基因的转录水平很高，但 SoxT1A 突变体仍不能进行硫氧化，这表明 SoxT1A 将硫输送到细胞质中进行进一步氧化。SoxT1B 作为转录抑制剂 SoxR 的信号转导单元，因为 SoxT1B 突变体由于转录水平低而不能进行硫氧化，除非 SoxR 也不存在。因此，SoxT1A 和 SoxT1B 在氧化硫代谢及其调节中发挥着重要但不同的作用。
