PDBsum entry 3qrx

Metal binding protein/toxin

PDB id: 3qrx

Contents

Protein chains

145 a.a.

20 a.a.

Metals

_CA ×4

Waters ×31

PDB id:

3qrx

Name:

Metal binding protein/toxin

Title:

Chlamydomonas reinhardtii centrin bound to melittin

Structure:

Centrin. Chain: a. Engineered: yes. Melittin. Chain: b. Fragment: residues 44-69. Synonym: allergen api m 3, allergen api m iii. Engineered: yes

Source:

Chlamydomonas reinhardtii. Organism_taxid: 3055. Gene: vfl2, chlredraft_159554. Expressed in: escherichia coli. Expression_system_taxid: 562. Synthetic: yes. Honeybee. Organism_taxid: 7460. Other_details: synthesized peptide corresponding to amino acids 44-

Resolution:

2.20Å R-factor: 0.294 R-free: 0.341

Authors:

E.R.Schreiter

Key ref:

L.d.e.l. .V.Sosa et al. (2011). The structure, molecular dynamics, and energetics of centrin-melittin complex. Proteins, 79, 3132-3143. PubMed id: 21989934

Date:

18-Feb-11 Release date: 26-Oct-11

Protein chain

P05434  (CATR_CHLRE) -  Caltractin from Chlamydomonas reinhardtii

Seq: 169 a.a.

Struc: 145 a.a.

Protein chain

P01501  (MEL_APIME) -  Melittin from Apis mellifera

Seq: 70 a.a.

Struc: 20 a.a.

Proteins 79:3132-3143 (2011)

PubMed id: 21989934

The structure, molecular dynamics, and energetics of centrin-melittin complex.

L.d.e.l. .V.Sosa, E.Alfaro, J.Santiago, D.Narváez, M.C.Rosado, A.Rodríguez, A.M.Gómez, E.R.Schreiter, B.Pastrana-Ríos.

ABSTRACT

Centrin is a calcium binding protein (CaBP) belonging to the EF-hand superfamily. As with other proteins within this family, centrin is a calcium sensor with multiple biological target proteins. We chose to study Chlamydomonas reinhardtii centrin (Crcen) and its interaction with melittin (MLT) as a model for CaBP complexes due to its amphipathic properties. Our goal was to determine the molecular interactions that lead to centrin-MLT complex formation, their relative stability, and the conformational changes associated with the interaction, when compared to the single components. For this, we determined the thermodynamic parameters that define Crcen-MLT complex formation. Two-dimensional infrared (2D IR) correlation spectroscopy were used to study the amide I', I'*, and side chain bands for (13)C-Crcen, MLT, and the (13)C-Crcen-MLT complex. This approach resulted in the determination of MLT's increased helicity, while centrin was stabilized within the complex. Herein we provide the first complete molecular description of centrin-MLT complex formation and the dissociation process. Also, discussed is the first structure of a CaBP-MLT complex by X-ray crystallography, which shows that MLT has a different binding orientation than previously characterized centrin-bound peptides. Finally, all of the experimental results presented herein are consistent with centrin maintaining an extended conformation while interacting with MLT. The molecular implications of these results are: (1) the recognition of hydrophobic contacts as requirements for initial binding, (2) minimum electrostatic interactions within the C-terminal end of the peptide, and (3) van der Waals interactions within MLTs N-terminal end are required for complex formation.