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Engineering Membranes in Escherichia coli: The Magnetosome, LemA Protein Family and Outer Membrane Vesicles

Juodeikis, Rokas (2016) Engineering Membranes in Escherichia coli: The Magnetosome, LemA Protein Family and Outer Membrane Vesicles. Doctor of Philosophy (PhD) thesis, University of Kent. (KAR id:61062)

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Abstract

Magnetosomes are membranous organelles found in magnetotactic bacteria (MTB). The organelle consist of ferromagnetic crystals housed within a lipid bilayer chained together by an actin-like filament and allows MTB to orient within magnetic fields. The genetic information required to produce these organelles has been linked to four different operons, encoding for 30 genes. These membranous organelles and the magnetic minerals housed within have various biotechnological applications, therefore enhanced recombinant production of such structures in a model organism holds significant potential. The research described in this thesis is focuses on the production of recombinant magnetosomes in the model organism Escherichia coli.

Individual production of two different magnetosome proteins, MamQ or MamY, allowed the generation of various membranous structures in E. coli observed in 48.9% and 56.2% of the whole population of cells respectively. Combinations of these with MamI, MamL or MamB in a variety of combinations led to a variation in the phenotype observed. Bioinformatics analysis of MamQ led to the discovery of a novel membrane restructuring protein family, the LemA protein family, present in a broad range of bacteria. Four different LemA proteins from Bacillus megaterium, Clostridium kluyveri, Brucella melitensis or Pseudomonas aeruginosa were then produced in E. coli and the analysis of the resulting strains revealed the presence of novel intracellular membranous structures which vary in size, form and localisation. Furthermore, when attempts were made to target these proteins for the modification of the outer membrane, a mechanism for increased outer membrane vesicle generation was serendipitously discovered and different effects of these proteins were once again observed.

Together, the results described shows good evidence for recombinant magnetosome production in E. coli and opens a new avenue of membrane engineering in this commonly used organism. Such membranous structures have various biotechnological applications, such as enhanced metabolic engineering potential or specialised lipid vesicle production.

Item Type: Thesis (Doctor of Philosophy (PhD))
Thesis advisor: Warren, Martin
Uncontrolled keywords: Microbiology Magnetosome Membrane Synbio
Divisions: Faculties > Sciences > School of Biosciences
Depositing User: Users 1 not found.
Date Deposited: 28 Mar 2017 11:00 UTC
Last Modified: 23 Jan 2020 04:13 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/61062 (The current URI for this page, for reference purposes)
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