PDBsum entry 1boc

Calcium-binding protein

PDB id: 1boc

Contents

Protein chain

76 a.a. *

* Residue conservation analysis

PDB id:

1boc

Name:

Calcium-binding protein

Title:

The solution structures of mutant calbindin d9k's, as determined by nmr, show that the calcium binding site can adopt different folds

Structure:

Calbindin d9k. Chain: a. Engineered: yes

Source:

Bos taurus. Cattle. Organism_taxid: 9913. Organ: intestine

NMR struc:

29 models

Authors:

C.Johansson,M.Ullner,T.Drakenberg

Key ref:

C.Johansson et al. (1993). The solution structures of mutant calbindin D9k's, as determined by NMR, show that the calcium-binding site can adopt different folds. Biochemistry, 32, 8429-8438. PubMed id: 8357794 DOI: 10.1021/bi00084a007

Date:

23-Apr-93 Release date: 31-Oct-93

Protein chain

P02633  (S100G_BOVIN) -  Protein S100-G from Bos taurus

Seq: 79 a.a.

Struc: 76 a.a.*

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

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1021/bi00084a007

Biochemistry 32:8429-8438 (1993)

PubMed id: 8357794

The solution structures of mutant calbindin D9k's, as determined by NMR, show that the calcium-binding site can adopt different folds.

C.Johansson, M.Ullner, T.Drakenberg.

ABSTRACT

The complete 1H NMR assignments have been obtained for five mutant proteins of calbindin D9k and the three-dimensional solution structures determined for two of the mutants. The structures have been determined using distance geometry and simulated annealing, with distance constraints from NMR. All mutants have modifications in the first calcium-binding site of calbindin (the N-terminal site designated the pseudo-EF-hand). The 3D structure of the mutant with the most extensive modifications in the pseudo-EF-hand shows that the site has turned inside-out and coordinates calcium as in the normal EF-hand (the C-terminal site). In a pseudo-EF-hand loop the calcium is coordinated by main-chain carbonyls, whereas calcium in the normal EF-hand is coordinated by side-chain carboxylates. The 3D structures and 1H NMR assignments show that in order to accomplish a change in the coordinating ligands of the pseudo-EF-hand the loop must be 12 residues long and have glycine in the sixth position. It does, however, seem possible to have alanine instead of aspartic acid in the first calcium coordinating position. The overall global fold of the proteins has not been affected by the mutations in the calcium-binding site, as compared to the wild-type calbindin D9k [Kördel, J., Skelton, N. J., Akke, M., & Chazin, W. J. (1993) J. Mol. Biol. (in press)]. The structures consist of two helix-calcium-binding loop-helix motifs, the so called EF-hands, and the loops are connected by a short antiparallel beta-sheet. All helices are pairwise in an antiparallel orientation.