Rawlings, A.E., Bramble, J.P., Walker, R. et al. (3 more authors) (2014) Self-assembled MmsF proteinosomes control magnetite nanoparticle formation in vitro. Proceedings of the National Academy of Sciences of the United States of America (PNAS) ISSN 1091-6490, 111 (45). 16094 - 16099. ISSN 1091-6490
Abstract
Magnetotactic bacteria synthesize highly uniform intracellular magnetite nanoparticles through the action of several key biomineralization proteins. These proteins are present in a unique lipid-bound organelle (the magnetosome) that functions as a nanosized reactor in which the particle is formed. A master regulator protein of nanoparticle formation, magnetosome membrane specific F (MmsF), was recently discovered. This predicted integral membrane protein is essential for controlling the monodispersity of the nanoparticles in Magnetospirillum magneticum strain AMB-1. Two MmsF homologs sharing over 60% sequence identity, but showing no apparent impact on particle formation, were also identified in the same organism. We have cloned, expressed, and used these three purified proteins as additives in synthetic magnetite precipitation reactions. Remarkably, these predominantly α-helical membrane spanning proteins are unusually highly stable and water-soluble because they self-assemble into spherical aggregates with an average diameter of 36 nm. The MmsF assembly appears to be responsible for a profound level of control over particle size and iron oxide (magnetite) homogeneity in chemical precipitation reactions, consistent with its indicated role in vivo. The assemblies of its two homologous proteins produce imprecise various iron oxide materials, which is a striking difference for proteins that are so similar to MmsF both in sequence and hierarchical structure. These findings show MmsF is a significant, previously undiscovered, protein additive for precision magnetite nanoparticle production. Furthermore, the self-assembly of these proteins into discrete, soluble, and functional “proteinosome” structures could lead to advances in fields ranging from membrane protein production to drug delivery applications.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | Copyright 2014 National Academy of Sciences |
Keywords: | MmsF; proteinosome; magnetite; magnetosome; in vitro precipitation |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Chemistry (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 14 Dec 2015 16:47 |
Last Modified: | 14 Dec 2015 16:51 |
Published Version: | http://dx.doi.org/10.1073/pnas.1409256111 |
Status: | Published |
Publisher: | National Academy of Sciences |
Refereed: | Yes |
Identification Number: | 10.1073/pnas.1409256111 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:85666 |