PDBsum entry 1rcc

Iron storage

PDB id: 1rcc

Contents

Protein chain

171 a.a. *

Ligands

BET

Waters ×29

* Residue conservation analysis

PDB id:

1rcc

Name:

Iron storage

Title:

Bullfrog red cell l ferritin tartrate/mg/ph 5.5

Structure:

L ferritin. Chain: a. Engineered: yes. Mutation: yes

Source:

Rana catesbeiana. Bullfrog. Organism_taxid: 8400. Cell: red cell. Gene: cdna. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

24mer (from PQS)

Resolution:

2.40Å R-factor: 0.189 R-free: 0.272

Authors:

J.Trikha,E.C.Theil,N.M.Allewell

Key ref:

J.Trikha et al. (1995). High resolution crystal structures of amphibian red-cell L ferritin: potential roles for structural plasticity and solvation in function. J Mol Biol, 248, 949-967. PubMed id: 7760335

Date:

04-Aug-95 Release date: 14-Nov-95

Protein chain

P07797  (FRI3_LITCT) -  Ferritin, lower subunit from Lithobates catesbeianus

Seq: 173 a.a.

Struc: 171 a.a.*

* PDB and UniProt seqs differ at 4 residue positions (black crosses)

J Mol Biol 248:949-967 (1995)

PubMed id: 7760335

High resolution crystal structures of amphibian red-cell L ferritin: potential roles for structural plasticity and solvation in function.

J.Trikha, E.C.Theil, N.M.Allewell.

ABSTRACT

Ferritin is a highly conserved multisubunit protein in animals, plants and microbes which assembles with cubic symmetry and transports hydrated iron ions and protons to and from a mineralized core in the protein interior. We report here the high resolution structures of recombinant amphibian red-cell L ferritin and two mutants solved under two sets of conditions. In one mutant, Glu56, 57, 58 and 60 were replaced with Ala, producing a lag phase in the kinetics of iron uptake. In the second mutant, His25 was replaced with Tyr with, at most, subtle effects on function. A molecule of betaine, used in the purification, is bound in all structures at the 2-fold axis near the recently identified heme binding site of bacterioferritin and horse spleen L ferritin. Comparisons of the five amphibian structures identify two regions of the molecule in which conformational flexibility may be related to function. The positions and interactions of a set of 10 to 18 side-chains, most of which are on the inner surface of the protein, are sensitive both to solution conditions and to the Glu-->Ala mutation. A subset of these side-chains and a chain of ordered solvent molecules extends from the vicinity of Glu56 to 58 and Glu60 to the 3-fold channel in the wild type protein and may be involved in the transport of either iron or protons. The "spine of hydration" is disrupted in the Glu-->Ala mutant. In contrast, H25Y mutation shifts the positions of backbone atoms between the site of the mutation and the 4-fold axis and side-chain positions throughout the structure; the largest changes in the position of backbone atoms are in the DE loop and E helix, approximately 10 A from the mutation site. In combination, these results indicate that solvation, structural plasticity and cooperative structural changes may play a role in ferritin function. Analogies with the structure and function of ion channel proteins such as annexins are noted.