PDBsum entry 3cs1

Metal binding protein

PDB id: 3cs1

Contents

Protein chain

192 a.a. *

Waters ×65

* Residue conservation analysis

PDB id:

3cs1

Name:

Metal binding protein

Title:

Flagellar calcium-binding protein (fcabp) from t. Cruzi

Structure:

Flagellar calcium-binding protein. Chain: a. Synonym: fcabp, 1f8 protein, p24, 29 kda flagella protein, f29, 24 kda antigen, alc-1 antigen. Engineered: yes

Source:

Trypanosoma cruzi. Gene: fcabp. Expressed in: escherichia coli.

Resolution:

2.00Å R-factor: 0.216 R-free: 0.288

Authors:

J.B.Ames,J.E.Ladner,J.N.Wingard,H.Robinson,A.Fisher

Key ref:

J.N.Wingard et al. (2008). Structural insights into membrane targeting by the flagellar calcium-binding protein (FCaBP), a myristoylated and palmitoylated calcium sensor in Trypanosoma cruzi. J Biol Chem, 283, 23388-23396. PubMed id: 18559337

Date:

08-Apr-08 Release date: 24-Jun-08

Protein chain

P07749  (FCA1_TRYCR) -  Flagellar calcium-binding protein from Trypanosoma cruzi

Seq: 211 a.a.

Struc: 192 a.a.*

* PDB and UniProt seqs differ at 6 residue positions (black crosses)

J Biol Chem 283:23388-23396 (2008)

PubMed id: 18559337

Structural insights into membrane targeting by the flagellar calcium-binding protein (FCaBP), a myristoylated and palmitoylated calcium sensor in Trypanosoma cruzi.

J.N.Wingard, J.Ladner, M.Vanarotti, A.J.Fisher, H.Robinson, K.T.Buchanan, D.M.Engman, J.B.Ames.

ABSTRACT

The flagellar calcium-binding protein (FCaBP) of the protozoan Trypanosoma cruzi is targeted to the flagellar membrane where it regulates flagellar function and assembly. As a first step toward understanding the Ca(2+)-induced conformational changes important for membrane-targeting, we report here the x-ray crystal structure of FCaBP in the Ca(2+)-free state determined at 2.2A resolution. The first 17 residues from the N terminus appear unstructured and solvent-exposed. Residues implicated in membrane targeting (Lys-19, Lys-22, and Lys-25) are flanked by an exposed N-terminal helix (residues 26-37), forming a patch of positive charge on the protein surface that may interact electrostatically with flagellar membrane targets. The four EF-hands in FCaBP each adopt a "closed conformation" similar to that seen in Ca(2+)-free calmodulin. The overall fold of FCaBP is closest to that of grancalcin and other members of the penta EF-hand superfamily. Unlike the dimeric penta EF-hand proteins, FCaBP lacks a fifth EF-hand and is monomeric. The unstructured N-terminal region of FCaBP suggests that its covalently attached myristoyl group at the N terminus may be solvent-exposed, in contrast to the highly sequestered myristoyl group seen in recoverin and GCAP1. NMR analysis demonstrates that the myristoyl group attached to FCaBP is indeed solvent-exposed in both the Ca(2+)-free and Ca(2+)-bound states, and myristoylation has no effect on protein structure and folding stability. We propose that exposed acyl groups at the N terminus may anchor FCaBP to the flagellar membrane and that Ca(2+)-induced conformational changes may control its binding to membrane-bound protein targets.