The dmsEFABGH operon encodes an essential and modular electron transfer pathway for extracellular iodate reduction by Shewanella oneidensis MR-1.

Autor: Hou L; Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei, China., Zheng B; Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei, China., Jiang Z; Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei, China., Hu Y; Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei, China., Shi L; Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei, China.; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, Hubei, China., Dong Y; Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei, China.; State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, Hubei, China., Jiang Y; Department of Biological Sciences and Technology, School of Environmental Studies, China University of Geosciences, Wuhan, Hubei, China.; Hubei Key Laboratory of Wetland Evolution & Eco-Restoration, Wuhan, Hubei, China.
Jazyk: angličtina
Zdroj: Microbiology spectrum [Microbiol Spectr] 2024 Aug 06; Vol. 12 (8), pp. e0051224. Date of Electronic Publication: 2024 Jun 25.
DOI: 10.1128/spectrum.00512-24
Abstrakt: Extracellular iodate reduction by Shewanella spp. contributes to iodide generation in the biogeochemical cycling of iodine. However, there is a disagreement on whether Shewanella spp. use different extracellular electron transfer pathways with dependence on electron donors in iodate reduction. In this study, a series of gene deletion mutants of Shewanella oneidensis MR-1 were created to investigate the roles of dmsEFABGH , mtrCAB, and so4357-so4362 operons in iodate reduction. The iodate-reducing activity of the mutants was tested with lactate, formate, and H 2 as the sole electron donors, respectively. In the absence of single- dms gene, iodate reduction efficiency of the mutants was only 12.9%-84.0% with lactate at 24 hours, 22.1%-85.9% with formate at 20 hours, and 19.6%-57.7% with H 2 at 42 hours in comparison to complete reduction by the wild type. Progressive inhibition of iodate reduction was observed when the dms homolog from the so4357-so4362 operon was deleted in the single- dms gene mutants. This result revealed complementation of dmsEFABGH by so4357-so4362 at the single-gene level, indicating modularity of the extracellular electron transfer pathway encoded by dmsEFABGH operon. Under the conditions of all electron donors, significant inhibition of iodate reduction and accumulation of H 2 O 2 were detected for Δ mtrCAB . Collectively, these results demonstrated that the dmsEFABGH operon encodes an essential and modular iodate-reducing pathway without electron donor dependence in S. oneidensis MR-1. The mtrCAB operon was involved in H 2 O 2 elimination with all electron donors. The findings in this study improved the understanding of molecular mechanisms underlying extracellular iodate reduction.IMPORTANCEIodine is an essential trace element for human and animals. Recent studies revealed the contribution of microbial extracellular reduction of iodate in biogeochemical cycling of iodine. Multiple reduced substances can be utilized by microorganisms as energy source for iodate reduction. However, varied electron transfer pathways were proposed for iodate reduction with different electron donors in the model strain Shewanella oneidensis MR-1. Here, through a series of gene deletion and iodate reduction experiments, we discovered that the dmsEFABGH operon was essential for iodate reduction with at least three electron donors, including lactate, formate, and H 2 . The so4357-so4362 operon was first demonstrated to be capable of complementing the function of dmsEFABGH at single-gene level.
Competing Interests: The authors declare no conflict of interest.
Databáze: MEDLINE
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