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Abstract
Paradigms of metabolic strategies employed by photoautotrophic marine picocyanobacteria have been challenged in recent years. Based on genomic annotations, picocyanobacteria are predicted to assimilate organic nutrients via ATP-binding cassette importers, a process mediated by substrate-binding proteins. We report the functional characterisation of a modified sugar-binding protein, MsBP, from a marine Synechococcus strain, MITS9220. Ligand screening of MsBP shows a specific affinity for zinc (KD ~ 1.3 μM) and a preference for phosphate-modified sugars, such as fructose-1,6-biphosphate, in the presence of zinc (KD ~ 5.8 μM). Our crystal structures of apo MsBP (no zinc or substrate-bound) and Zn-MsBP (with zinc-bound) show that the presence of zinc induces structural differences, leading to a partially-closed substrate-binding cavity. The Zn-MsBP structure also sequesters several sulphate ions from the crystallisation condition, including two in the binding cleft, appropriately placed to mimic the orientation of adducts of a biphosphate hexose. Combined with a previously unseen positively charged binding cleft in our two structures and our binding affinity data, these observations highlight novel molecular variations on the sugar-binding SBP scaffold. Our findings lend further evidence to a proposed sugar acquisition mechanism in picocyanobacteria alluding to a mixotrophic strategy within these ubiquitous photosynthetic bacteria.
Original language | English |
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Article number | 4805 |
Pages (from-to) | 1-16 |
Number of pages | 16 |
Journal | Scientific Reports |
Volume | 12 |
Issue number | 1 |
DOIs | |
Publication status | Published - Dec 2022 |
Bibliographical note
Copyright the Author(s) 2022. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.Fingerprint
Dive into the research topics of 'Novel functional insights into a modified sugar-binding protein from Synechococcus MITS9220'. Together they form a unique fingerprint.Projects
- 1 Finished
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Do binding proteins allow cyanobacteria to scavenge diverse nutrients?
1/02/20 → 31/01/23
Project: Other