Polyviou, D., Machelett, M.M., Hitchcock, A. et al. (5 more authors) (2018) Structural and functional characterization of IdiA/FutA (Tery_3377), an iron-binding protein from the ocean diazotroph Trichodesmium erythraeum. Journal of Biological Chemistry, 293 (47). pp. 18099-18109. ISSN 0021-9258
Abstract
Atmospheric nitrogen fixation by photosynthetic cyanobacteria (diazotrophs) strongly influences oceanic primary production and in turn affects global biogeochemical cycles. Species of the genus Trichodesmium are major contributors to marine diazotrophy, accounting for a significant proportion of the fixed nitrogen in tropical and subtropical oceans. However, Trichodesmium spp. are metabolically constrained by the availability of iron, an essential element for both the photosynthetic apparatus and the nitrogenase enzyme. Survival strategies in low-iron environments are typically poorly characterized at the molecular level, because these bacteria are recalcitrant to genetic manipulation. Here, we studied a homolog of the iron deficiency-induced A (IdiA)/ferric uptake transporter A (FutA) protein, Tery_3377, which has been used as an in situ iron-stress biomarker. IdiA/FutA has an ambiguous function in cyanobacteria, with its homologs hypothesized to be involved in distinct processes depending on their cellular localization. Using signal sequence fusions to GFP and heterologous expression in the model cyanobacterium Synechocystis sp. PCC 6803, we show that Tery_3377 is targeted to the periplasm by the twin-arginine translocase and can complement the deletion of the native Synechocystis ferric-iron ABC transporter periplasmic binding protein (FutA2). EPR spectroscopy revealed that purified recombinant Tery_3377 has specificity for iron in the Fe3+ state, and an X-ray crystallography–determined structure uncovered a functional iron substrate–binding domain, with Fe3+ pentacoordinated by protein and buffer ligands. Our results support assignment of Tery_3377 as a functional FutA subunit of an Fe3+ ABC transporter but do not rule out dual IdiA function.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2018 Polyviou et al. Author's Choice—Final version open access under the terms of the Creative Commons CC-BY license. https://creativecommons.org/licenses/by/4.0/ |
Keywords: | ABC transporter; X-ray crystallography; iron; cyanobacteria; microscopy; diazotroph; iron deficiency |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > School of Biosciences (Sheffield) > Department of Molecular Biology and Biotechnology (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 08 Mar 2019 10:08 |
Last Modified: | 08 Mar 2019 10:08 |
Published Version: | http://dx.doi.org/10.1074/jbc.RA118.001929 |
Status: | Published |
Publisher: | American Society for Biochemistry and Molecular Biology |
Refereed: | Yes |
Identification Number: | 10.1074/jbc.RA118.001929 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:142090 |