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The DsrD functional marker protein is an allosteric activator of the DsrAB dissimilatory sulfite reductase
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Resumo(s)
Dissimilatory sulfur metabolism was recently shown to be much more widespread among bacteria and archaea than previously believed. One of the key pathways involved is the dsr pathway that is responsible for sulfite reduction in sulfate-, sulfur-, thiosulfate-, and sulfite-reducing organisms, sulfur disproportionators and organosulfonate degraders, or for the production of sulfite in many photo- and chemotrophic sulfur-oxidizing prokaryotes. The key enzyme is DsrAB, the dissimilatory sulfite reductase, but a range of other Dsr proteins is involved, with different gene sets being present in organisms with a reductive or oxidative metabolism. The dsrD gene codes for a small protein of unknown function and has been widely used as a functional marker for reductive or disproportionating sulfur metabolism, although in some cases this has been disputed. Here, we present in vivo and in vitro studies showing that DsrD is a physiological partner of DsrAB and acts as an activator of its sulfite reduction activity. DsrD is expressed in respiratory but not in fermentative conditions and a ΔdsrD deletion strain could be obtained, indicating that its function is not essential. This strain grew less efficiently during sulfate and sulfite reduction. Organisms with the earliest forms of dsrAB lack the dsrD gene, revealing that its activating role arose later in evolution relative to dsrAB.
Descrição
Funding Information: ACKNOWLEDGMENTS. We thank Christiane Dahl from the University of Bonn for critically reading the manuscript. This work was funded by the Fundac¸ão para a Ciência e Tecnologia (Portugal) through Fellowships PD/BD/135488/2018 (A.C.C.B.), PD/BD/128204/2016 (D.F.), and SFRH/BPD/79823/2011 (S.S.V.); Grants PTDC/BIA-MIC/6512/2014 and PTDC/BIA-BQM/29118/2017; and Research unit Molecular and Structural Microbiology (MOSTMICRO-ITQB) (Grants UIDB/04612/ 2020 and UIDP/04612/2020). The European Union’s Horizon 2020 Research and Innovation Program (Grant Agreement No. 810856) is also acknowledged. Publisher Copyright: © 2022 National Academy of Sciences. All rights reserved.
Palavras-chave
Allosteric activation Dissimilatory sulfite reductase Sulfate-reducing bacteria Sulfur disproportionation Sulfur metabolism General