TY  - JOUR
AU  - Haikarainen, T.
AU  - Paturi, P.
AU  - Linden, J.
AU  - Haataja, S.
AU  - Meyer-Klaucke, W.
AU  - Finne, J.
AU  - Papageorgiou, A. C.
AU  - DESY
TI  - Magnetic properties and structural characterization of iron oxide nanoparticles formed by Streptococcus suis Dpr and four mutants
JO  - Journal of biological inorganic chemistry
VL  - 16
SN  - 0949-8257
CY  - Berlin
PB  - Springer
M1  - PHPPUBDB-19320
SP  - 799-807
PY  - 2011
AB  - 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.
KW  - Bacterial Proteins: chemistry
KW  - Bacterial Proteins: genetics
KW  - Bacterial Proteins: metabolism
KW  - Ceruloplasmin: metabolism
KW  - Crystallography, X-Ray
KW  - Ferric Compounds: chemistry
KW  - Ferric Compounds: metabolism
KW  - Ferritins: metabolism
KW  - Magnetics
KW  - Nanoparticles: chemistry
KW  - Point Mutation
KW  - Protein Engineering
KW  - Spectroscopy, Mossbauer
KW  - Streptococcus suis: chemistry
KW  - Streptococcus suis: genetics
KW  - Streptococcus suis: metabolism
KW  - Bacterial Proteins (NLM Chemicals)
KW  - Ferric Compounds (NLM Chemicals)
KW  - ferric oxide (NLM Chemicals)
KW  - Ferritins (NLM Chemicals)
KW  - Ceruloplasmin (NLM Chemicals)
LB  - PUB:(DE-HGF)16
C6  - pmid:21487937
UR  - <Go to ISI:>//WOS:000290773500012
DO  - DOI:10.1007/s00775-011-0781-z
UR  - https://bib-pubdb1.desy.de/record/95049
ER  -