Reduction-dependent siderophore assimilation in a model pennate diatom

TitleReduction-dependent siderophore assimilation in a model pennate diatom
Publication TypeJournal Article
Year of Publication2019
AuthorsCoale T.H, Moosburner M., Horak A., Obornik M., Barbeau K.A, Allen A.E
Volume116
Pagination23609-23617
Date Published2019/11
Type of ArticleArticle
ISBN Number0027-8424
Accession NumberWOS:000498683000040
Keywordsacquisition; amphiphilic; diatom; ferric reductase; iron acquisition; Iron-binding ligands; marine; organic-ligands; pacific; phaeodactylum-tricornutum; phytoplankton; Science & Technology - Other Topics; siderophore; siderophores; thalassiosira-oceanica; transport
Abstract

Iron uptake by diatoms is a biochemical process with global biogeochemical implications. In large regions of the surface ocean diatoms are both responsible for the majority of primary production and frequently experiencing iron limitation of growth. The strategies used by these phytoplankton to extract iron from seawater constrain carbon flux into higher trophic levels and sequestration into sediments. In this study we use reverse genetic techniques to target putative iron-acquisition genes in the model pennate diatom Phaeodactylum tricornutum. We describe components of a reduction-dependent siderophore acquisition pathway that relies on a bacterial-derived receptor protein and provides a viable alternative to inorganic iron uptake under certain conditions. This form of iron uptake entails a close association between diatoms and siderophore-producing organisms during low-iron conditions. Homologs of these proteins are found distributed across diatom lineages, suggesting the significance of siderophore utilization by diatoms in the marine environment. Evaluation of specific proteins enables us to confirm independent iron-acquisition pathways in diatoms and characterize their preferred substrates. These findings refine our mechanistic understanding of the multiple iron-uptake systems used by diatoms and help us better predict the influence of iron speciation on taxa-specific iron bioavailability.

DOI10.1073/pnas.1907234116
Student Publication: 
No