Macquarie University
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Molecular mechanisms of nutrient uptake in marine microbial ecosystems

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posted on 2022-03-29, 03:15 authored by Andrew George McLeish
Unicellular cyanobacteria are highly diverse, abundant and ubiquitous in the global oceans. Investigating the range and magnitude of organic compound transport in these organisms will help define pathways of energy and nutrient cycling in marine ecosystems.ABC membrane transport systems utilise a periplasmic binding protein (PBP) to confer substrate specificity. These PBPs are thus ideal targets to study the ecological significance of predicted amino acid transporters. Twelve PBPs were investigated that group into three orthologous gene clusters with putative ligands: branched-chain amino acids;carbohydrates and amino acids; or amino acids, based on homology predictions.A high-throughput recombinant expression strategy enabled a protein from each cluster to be successfully heterologously expressed and purified. Differential scanning fluorimetry (DSF) analysis revealed that "SW840" binds a broad range of amino acids, aspredicted. "SC634" on the other hand was found to bind with formate and formaldehyde, not the predicted ligand of branched-chain amino acids.This work provides important evidence of the specific ligand binding characteristics for each transporter. Future work to elucidate the cellular fate of these compounds is proposed. The ability of cyanobacteria, often considered to be obligatory phototrophs, tosalvage organic compounds may provide a competitive advantage in marine ecosystems.


Table of Contents

Chapter 1. Introduction -- Chapter 2. Experimental design, materials and methods -- Chapter 3. Expression, purification, and characterisation of cynobacterial PBPs -- Chapter 4. Discussion


Bibliography: pages 52-61 Theoretical thesis.

Awarding Institution

Macquarie University

Degree Type

Thesis MRes


MRes, Macquarie University, Faculty of Science and Engineering, Department of Chemistry and Biomolecular Sciences

Department, Centre or School

Department of Chemistry and Biomolecular Sciences

Year of Award


Principal Supervisor

Bhumika Shah

Additional Supervisor 1

Ian Paulsen


Copyright Andrew George McLeish 2017 Copyright disclaimer:




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