Conflict of interest: This research was partially supported through B. P. O.'s personal salary.
Rational disruption of the oligomerization of the mini-ferritin E. coli DPS through protein-protein interface mutation†
Article first published online: 5 OCT 2011
Copyright © 2011 The Protein Society
Volume 20, Issue 11, pages 1907–1917, November 2011
How to Cite
Zhang, Y., Fu, J., Chee, S. Y., Ang, E. X. W. and Orner, B. P. (2011), Rational disruption of the oligomerization of the mini-ferritin E. coli DPS through protein-protein interface mutation. Protein Science, 20: 1907–1917. doi: 10.1002/pro.731
- Issue published online: 18 OCT 2011
- Article first published online: 5 OCT 2011
- Accepted manuscript online: 6 SEP 2011 12:49PM EST
- Manuscript Accepted: 26 AUG 2011
- Manuscript Revised: 24 AUG 2011
- Manuscript Received: 27 JUN 2011
- CBC start up grant and a Singapore Ministry of Education Academic Research Fund Tier 1 Grant. Grant Number: RG 53/06
- alanine shaving;
DNA-binding protein from starved cells (DPS), a mini-ferritin capable of self-assembling into a 12-meric nano-cage, was chosen as the basis for an alanine-shaving mutagenesis study to investigate the importance of key amino acid residues, located at symmetry-related protein-protein interfaces, in controlling protein stability and self-assembly. Nine mutants were designed through simple inspection, synthesized, and subjected to transmission electron microscopy, circular dichroism, size exclusion chromatography, and “virtual alanine scanning” computational analysis. The data indicate that many of these residues may be hot spot residues. Most remarkably, two residues, R83 and R133, were observed to shift the oligomerization state to ˜50% dimer. Based on the hypothesis that these two residues constitute a “hot strip,” located at the ferritin-like threefold axis, the double mutant was generated which completely shuts down detectable formation of 12-mer in solution, favoring a cooperatively folded dimer. The fact that this effect logically builds upon the single mutants emphasizes that complex self-assembly has the potential to be manipulated rationally. This study should have an impact on the fundamental understanding of the assembly of DPS protein cages specifically and protein quaternary structure in general. In addition, as there is much interest in applying these and similar systems to the templation of nano-materials and drug delivery, the ability to control this ferritin's oligomerization state and stability could prove especially valuable.