Journal Article

PHPPUBDB-19320

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Magnetic properties and structural characterization of iron oxide nanoparticles formed by Streptococcus suis Dpr and four mutants

Haikarainen, T. ; Paturi, P. ; Linden, J. ; Haataja, S. ; Meyer-Klaucke, W. ; Finne, J. ; Papageorgiou, A. C. ; DESY

2011
Springer Berlin

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Please use a persistent id in citations: doi:10.1007/s00775-011-0781-z

Abstract: Streptococcus suis Dpr belongs to the Dps family of bacterial and archaeal proteins that oxidize Fe(2+) to Fe(3+) to protect microorganisms from oxidative damage. The oxidized iron is subsequently deposited as ferrihydrite inside a protein cavity, resulting in the formation of an iron core. The size and the magnetic properties of the iron core have attracted considerable attention for nanotechnological applications in recent years. Here, the magnetic and structural properties of the iron core in wild-type Dpr and four cavity mutants were studied. All samples clearly demonstrated a superparamagnetic behavior in superconducting quantum interference device magnetometry and Mössbauer spectroscopy compatible with that of superparamagnetic ferrihydrite nanoparticles. However, all the mutants exhibited higher magnetic moments than the wild-type protein. Furthermore, measurement of the iron content with inductively coupled plasma mass spectrometry revealed a smaller amount of iron in the iron cores of the mutants, suggesting that the mutations affect nucleation and iron deposition inside the cavity. The X-ray crystal structures of the mutants revealed no changes compared with the wild-type crystal structure; thus, the differences in the magnetic moments could not be attributed to structural changes in the protein. Extended X-ray absorption fine structure measurements showed that the coordination geometry of the iron cores of the mutants was similar to that of the wild-type protein. Taken together, these results suggest that mutation of the residues that surround the iron storage cavity could be exploited to selectively modify the magnetic properties of the iron core without affecting the structure of the protein and the geometry of the iron core.

Keyword(s): Bacterial Proteins: chemistry (MeSH) ; Bacterial Proteins: genetics (MeSH) ; Bacterial Proteins: metabolism (MeSH) ; Ceruloplasmin: metabolism (MeSH) ; Crystallography, X-Ray (MeSH) ; Ferric Compounds: chemistry (MeSH) ; Ferric Compounds: metabolism (MeSH) ; Ferritins: metabolism (MeSH) ; Magnetics (MeSH) ; Nanoparticles: chemistry (MeSH) ; Point Mutation (MeSH) ; Protein Engineering (MeSH) ; Spectroscopy, Mossbauer (MeSH) ; Streptococcus suis: chemistry (MeSH) ; Streptococcus suis: genetics (MeSH) ; Streptococcus suis: metabolism (MeSH) ; Bacterial Proteins ; Ferric Compounds ; ferric oxide ; Ferritins ; Ceruloplasmin

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Contributing Institute(s):

1. European Molecular Biology Laboratory (EMBL)

Research Program(s):

1. DORIS Beamline K1.2 (POF2-54G13) (POF2-54G13)

Experiment(s):

1. DORIS Beamline K1.2 (DORIS III)

Appears in the scientific report 2011
Notes: (c) SBIC

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Database coverage:
; ; JCR ; No Author Disambiguation ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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