The Protein Journal

, Volume 33, Issue 3, pp 211–220

The C-Terminal Regions Have an Important Role in the Activity of the Ferroxidase Center and the Stability of Chlorobium tepidum Ferritin

  • Cristian Brito
  • Catalina Matias
  • Fernando D. González-Nilo
  • Richard K. Watt
  • Alejandro Yévenes
Article

DOI: 10.1007/s10930-014-9552-3

Cite this article as:
Brito, C., Matias, C., González-Nilo, F.D. et al. Protein J (2014) 33: 211. doi:10.1007/s10930-014-9552-3

Abstract

The recombinant Chlorobium tepidum ferritin (rCtFtn) is able to oxidize iron using ferroxidase activity but its ferroxidase activity is intermediate between the H-chain human ferritin and the L-chain human ferritin. The rCtFtn has an unusual C-terminal region composed of 12 histidine residues, as well as aspartate and glutamate residues. These residues act as potential metal ion ligands, and the rCtFtn homology model predicts that this region projects inside the protein cage. The rCtFtn also lacks a conserved Tyr residue in position 19. In order to know if those differences are responsible for the altered ferroxidase properties of rCtFtn, we introduced by site-directed mutagenesis a stop codon at position 166 and a Tyr residue replaced Ala19 in the gene of rCtFtn (rCtFtn 166). The rCtFtn166 keeps the canonical sequence considered important for the activity of this family of proteins. Therefore, we expected that rCtFtn 166 would possess similar properties to those described for this protein family. The rCtFtn 166 is able to bind, oxidize and store iron; and its activity is inhibit by Zn(II) as was described for other ferritins. However, the rCtFtn 166 possesses a decrease ferroxidase activity and protein stability compared with the wild type rCtFtn. The analysis of the Ala19Tyr rCtFtn shows that this change does not affect the kinetic of iron oxidation. Therefore, these results indicate that the C-terminal regions have an important role in the activity of the ferroxidase center and the stability of rCtFtn.

Keywords

Bacterial ferritin Ferroxidase center Site-directed mutagenesis Transmission electron microscopy 

Abbreviations

Bfr

Bacterioferritin

FC

Ferroxidase center

GdnHCl

Guanidine hydrochloride

IPTG

Isopropyl-β-d-thiogalactoside

MOPS

3-(N-morpholino)propane sulfonic acid

PMSF

Phenylmethane sulfonyl fluoride

TEM

Transmission electron microscopy

WT

Wild type

YF

Maximum fluorescence intensity changes emission

Copyright information

© Springer Science+Business Media New York 2014

Authors and Affiliations

  • Cristian Brito
    • 1
  • Catalina Matias
    • 2
  • Fernando D. González-Nilo
    • 1
  • Richard K. Watt
    • 2
  • Alejandro Yévenes
    • 3
  1. 1.Facultad de Ciencias Biológicas, Centro de Bioinformática y Biología IntegrativaUniversidad Andrés BelloSantiagoChile
  2. 2.Department of Chemistry and BiochemistryBrigham Young UniversityProvoUSA
  3. 3.Departamento de Química Física, Facultad de QuímicaPontificia Universidad Católica de ChileSantiagoChile

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