Ferritin is a natural protein cage found in numerous organisms throughout the three kingdoms of life. Ferritin from the archaeon Archeoglobus fulgidus was expressed in E. coli and purified. This protein cage is obtained by the self-assembly of 24 subunits in the presence of divalent ions in solution. A mutant of this ferritin was also purified. While the natural protein has a tetrahedral geometry and one pore on each side, the mutant has an octahedral geometry and no pores. The protein cages were loaded with iron in vitro and thoroughly characterized with ATR, XRD, DLS and TEM. A variant of the ferritin subunit was also characterized. This variant has the m6A peptide attached to it. This peptide is derived from a protein found in the magnetotactic bacterium Magnetospirillum magneticum (AMB-1) and it is believed to play a role in magnetite nucleation. Results show small amounts of magnetite in some of the cages, and a prevalence of ferrihydrite in most of the samples. Nanoparticle-protein complexes were obtained with high stability and a narrow size distribution.
La ferritina è una gabbia proteica naturale, presente in numerosi organismi sia eucarioti che procarioti. La ferritina dell'archeobatterio Archaeoglobus fulgidus è stata espressa in E. coli e purificata. La gabbia proteica è ottenuta dall' auto-assemblaggio di 24 unità in presenza di ioni divalenti in soluzione. È stato prodotto anche un mutante di questa ferritina. Mentre la proteina naturale ha una geometria tetraedrica e un poro su ogni faccia, questo mutante presenta una geometria ottaedrica e nessun poro. Le gabbie proteiche sono state caricate con ioni ferro in vitro e caratterizzate con ATR, XRD, DLS e TEM. È stata caratterizzata anche una variante dell'unità di ferritina, con attaccato il peptide m6A. Questo peptide è derivato da una proteina presente nel batterio magnetotattico Magnetospirillum magneticum (AMB-1) ed è ritenuta un agente importante nella nucleazione di cristalli di magnetite. I risultati mostrano una piccola quantità di magnetite in alcuni campioni, e una prevalenza di ferridrite nella maggior parte dei campioni. Sono stati ottenuti dei complessi nanoparticella-proteina ad alta stabilità e con una stretta distribuzione delle dimensioni.
Synthesis and characterization of iron oxide nanoparticles from bacterial factories
LEOPARDI, LORENZO
2018/2019
Abstract
Ferritin is a natural protein cage found in numerous organisms throughout the three kingdoms of life. Ferritin from the archaeon Archeoglobus fulgidus was expressed in E. coli and purified. This protein cage is obtained by the self-assembly of 24 subunits in the presence of divalent ions in solution. A mutant of this ferritin was also purified. While the natural protein has a tetrahedral geometry and one pore on each side, the mutant has an octahedral geometry and no pores. The protein cages were loaded with iron in vitro and thoroughly characterized with ATR, XRD, DLS and TEM. A variant of the ferritin subunit was also characterized. This variant has the m6A peptide attached to it. This peptide is derived from a protein found in the magnetotactic bacterium Magnetospirillum magneticum (AMB-1) and it is believed to play a role in magnetite nucleation. Results show small amounts of magnetite in some of the cages, and a prevalence of ferrihydrite in most of the samples. Nanoparticle-protein complexes were obtained with high stability and a narrow size distribution.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/152034