Two novel zinc and cobalt-responsive proteins in marine eukaryotic phytoplankton and implications for Zn scarcity in the surface oceans

ABSTRACT: Observations of scarce surface ocean concentrations of dissolved zinc (Zn) have raised the possibility that Zn may co-limit the growth of oceanic phytoplankton, yet testing this hypothesis has been difficult because Zn is highly prone to contamination. Biomarkers of micro-nutrient stress can serve as an alternate means to assay, though biomarker proteins for Zn stress in marine algae are currently uncharacterized. In this study we identified two Zn-responsive proteins in four marine diatom species that became abundant under Zn and Co limitation, but were scarce or undetectable in replete conditions. We refer to these proteins as ZCRP-A and ZCRP-B (Zn/Co Responsive Protein A and B). Sequence similarity of ZCRP-A to the Escherichia coli model COG0523 protein YjiA suggests a Zn2+ binding capability using conserved metal binding sites. Cellular localization by fluorescent tagging and overexpression of these proteins showed that ZCRP-B is part of a membrane-bound transport complex and that ZCRP-A serves as a Zn/Co chaperone with a chloroplastic target. These results imply that ZCRP-A and ZCRP-B are important in intracellular Zn trafficking and high-affinity transport, respectively. Metaproteomic detection of ZCRP-A and ZCRP-B homologs in a variety of eukaryotic protists along a South Pacific Ocean transect demonstrated that both proteins were more abundant in the euphotic zone (0-200m) where dZn and dCo were scarce. These findings describe widely distributed marine algal proteins linked to Zn and Co metabolism that together contribute to our understanding of Zn homeostasis in important marine phytoplankton.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Phaeodactylum Tricornutum (strain Ccap 1055/1) Thalassiosira Pseudonana Ccmp1335 Pseudo-nitzschia Delicatissima Chaetoceros Sp.

SUBMITTER: Riss Kellogg  

LAB HEAD: Mak A. Saito

PROVIDER: PXD026953 | Pride | 2022-03-02

REPOSITORIES: Pride