Mineral-respiring bacteria use a process called extracellular electron transfer to route their respiratory electron transport chain to insoluble electron acceptors on the exterior of the cell. We recently characterized a flavin-based extracellular electron transfer system that is present in the foodborne pathogen Listeria monocytogenes, as well as many other Gram-positive bacteria, and which highlights a more generalized role for extracellular electron transfer in microbial metabolism. Here we identify a family of putative extracellular reductases that possess a conserved posttranslational flavinylation modification. Phylogenetic analyses suggest that divergent flavinylated extracellular reductase subfamilies possess distinct and often unidentified substrate specificities. We show that flavinylation of a member of the fumarate reductase subfamily allows this enzyme to receive electrons from the extracellular electron transfer system and support L. monocytogenes growth. We demonstrate that this represents a generalizablemechanism by finding that a L. monocytogenes strain engineered to express a flavinylated extracellular urocanate reductase uses urocanate by a related mechanism and to a similar effect. These studies thus identify an enzyme family that exploits a modular flavin-based electron transfer strategy to reduce distinct extracellular substrates and support a multifunctional view of the role of extracellular electron transfer activities in microbial physiology.
|Number of pages||8|
|Journal||Proceedings of the National Academy of Sciences of the United States of America|
|State||Published - Dec 26 2019|
Bibliographical noteFunding Information:
of the National Institutes of Health (1P01AI063302 to D.A.P., 1R01AI27655 to D.A.P., R56AI132410 to S.E.F.D., and F32AI136389 to S.H.L.). A mass spectrometer used in this study was purchased with NIH support (grant 1S10OD020062-01). R.M and J.F.B. were supported by a grant from the Innovative Genomics Institute at Berkeley. We thank Michael Marletta for thoughtful input.
ACKNOWLEDGMENTS. Research reported in this publication was supported by funding from the National Institute of Allergy and Infectious Diseases
© 2019 National Academy of Sciences. All rights reserved.
- Bacterial pathogenesis
- Cellular respiration
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