Facey, JA, Steele, JR, Violi, JP, Mitrovic, SM & Cranfield, C 2019, 'An examination of microcystin-LR accumulation and toxicity using tethered bilayer lipid membranes (tBLMs).', Toxicon, vol. 158, pp. 51-56.View/Download from: Publisher's site
Microcystin-LR (MC-LR) is a potent cyanobacterial toxin responsible for animal and human poisonings worldwide. MC-LR is found in organisms throughout the foodweb, however there is conjecture regarding whether it biomagnifies. Few studies have investigated how MC-LR interacts with lipid membranes, a determinant of biomagnification potential. We tested whether 1 μM MC-LR irreversibly associates with lipid bilayers or causes the creation of pore defects upon short and long-term exposure. Using tethered bilayer lipid membranes (tBLMs), we observed an increase in membrane conduction in tBLMs, representing an interaction of microcystin-LR with the lipid bilayer and a change in membrane packing properties. However, there were minimal changes in membrane capacitance upon short and long-term exposure, and MC-LR exhibited a rapid off-rate. Upon 24 h exposure to the toxin, no lipophilic multimeric complexes were detected capable of altering the toxin's off-rate. There was no evidence of the creation of new pores. This study demonstrates that MC-LR does not irreversibly imbed itself into lipids membranes after short or long-term exposure and suggests MC-LR does not biomagnify through the food web via lipid storage.
Widjaja, M, Harvey, KL, Hagemann, L, Berry, IJ, Jarocki, V, Raymond, BBA, Tacchi, JL, Gründel, A, Steele, JR, Padula, MP, Charles, IG, Dumke, R & Djordjevic, SP 2017, 'Elongation factor Tu is a multifunctional and processed moonlighting protein.', Scientific Reports, vol. 7, no. 1, pp. 1-17.View/Download from: UTS OPUS or Publisher's site
Many bacterial moonlighting proteins were originally described in medically, agriculturally, and commercially important members of the low G + C Firmicutes. We show Elongation factor Tu (Ef-Tu) moonlights on the surface of the human pathogens Staphylococcus aureus (SaEf-Tu) and Mycoplasma pneumoniae (MpnEf-Tu), and the porcine pathogen Mycoplasma hyopneumoniae (MhpEf-Tu). Ef-Tu is also a target of multiple processing events on the cell surface and these were characterised using an N-terminomics pipeline. Recombinant MpnEf-Tu bound strongly to a diverse range of host molecules, and when bound to plasminogen, was able to convert plasminogen to plasmin in the presence of plasminogen activators. Fragments of Ef-Tu retain binding capabilities to host proteins. Bioinformatics and structural modelling studies indicate that the accumulation of positively charged amino acids in short linear motifs (SLiMs), and protein processing promote multifunctional behaviour. Codon bias engendered by an A + T rich genome may influence how positively-charged residues accumulate in SLiMs.
Berry, IJ, Steele, JR, Padula, MP & Djordjevic, SP 2016, 'The Application of terminomics for the identification of protein start sites and proteoforms in bacteria.', Proteomics, vol. 16, no. 2, pp. 257-272.View/Download from: UTS OPUS or Publisher's site
Protein terminomics, or the study of amino acids sequences at the protein amino or carboxyl
terminus has rapidly evolved as a proteomic discipline due to significant methodological improvements
in the labelling and recovery of terminal peptides as well as the increased speed
and sensitivity of current mass spectrometry instrumentation. The most significant benefi-
ciaries of these developments include an increased awareness and understanding of complex
proteolytic cascades that regulate key biological processes and in genome annotation. Most terminomics
research to date has focused on gaining insight into important biological processes
such as inflammation, wound healing and cancer. The application of terminomics to the study
of important biological questions in prokaryotes is gaining traction. Here we review current
applications and progress of terminomics in prokaryotes, discuss the significance of protease
research in bacterial pathogenesis and protein maturation, and suggest novel applications of
terminomics in the study of infectious disease.