5v5k

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Crystal structure of ferritin E65R mutant from hyperthermophilic archaeon Archaeoglobus fulgidus

Structural highlights

5v5k is a 8 chain structure with sequence from Archaeoglobus fulgidus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 3.08Å
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

O29424_ARCFU

Publication Abstract from PubMed

Protein cage self-assembly enables encapsulation and sequestration of small molecules, macromolecules, and nanomaterials for many applications in bionanotechnology. Notably, wild-type thermophilic ferritin from Archaeoglobus fulgidus (AfFtn) exists as a stable dimer of four-helix bundle proteins at a low ionic strength, and the protein forms a hollow assembly of 24 protomers at a high ionic strength ( approximately 800 mM NaCl). This assembly process can also be initiated by highly charged gold nanoparticles (AuNPs) in solution, leading to encapsulation. These data suggest that salt solutions or charged AuNPs can shield unfavorable electrostatic interactions at AfFtn dimer-dimer interfaces, but specific "hot-spot" residues controlling assembly have not been identified. To investigate this further, we computationally designed three AfFtn mutants (E65R, D138K, and A127R) that introduce a single positive charge at sites along the dimer-dimer interface. These proteins exhibited different assembly kinetics and thermodynamics, which were ranked in order of increasing 24mer propensity: A127R < wild type < D138K << E65R. E65R assembled into the 24mer across a wide range of ionic strengths (0-800 mM NaCl), and the dissociation temperature for the 24mer was 98 degrees C. X-ray crystal structure analysis of the E65R mutant identified a more compact, closed-pore cage geometry. A127R and D138K mutants exhibited wild-type ability to encapsulate and stabilize 5 nm AuNPs, whereas E65R did not encapsulate AuNPs at the same high yields. This work illustrates designed protein cages with distinct assembly and encapsulation properties.

Thermophilic Ferritin 24mer Assembly and Nanoparticle Encapsulation Modulated by Interdimer Electrostatic Repulsion.,Pulsipher KW, Villegas JA, Roose BW, Hicks TL, Yoon J, Saven JG, Dmochowski IJ Biochemistry. 2017 Jul 18;56(28):3596-3606. doi: 10.1021/acs.biochem.7b00296., Epub 2017 Jul 6. PMID:28682599^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Pulsipher KW, Villegas JA, Roose BW, Hicks TL, Yoon J, Saven JG, Dmochowski IJ. Thermophilic Ferritin 24mer Assembly and Nanoparticle Encapsulation Modulated by Interdimer Electrostatic Repulsion. Biochemistry. 2017 Jul 18;56(28):3596-3606. doi: 10.1021/acs.biochem.7b00296., Epub 2017 Jul 6. PMID:28682599 doi:http://dx.doi.org/10.1021/acs.biochem.7b00296