PDBsum entry 2kgb

Contractile protein/ca binding protein

PDB id: 2kgb

Contents

Protein chains

89 a.a. *

20 a.a. *

Metals

_CA

* Residue conservation analysis

PDB id:

2kgb

Name:

Contractile protein/ca binding protein

Title:

Nmr solution of the regulatory domain cardiac f77w-troponin c in complex with the cardiac troponin i 144-163 switch peptide

Structure:

Troponin c, slow skeletal and cardiac muscles. Chain: c. Fragment: regulatory domain. Synonym: tn-c. Engineered: yes. Mutation: yes. Troponin i, cardiac muscle. Chain: i. Synonym: cardiac troponin i.

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: tnnc1, tnnc. Expressed in: escherichia coli. Expression_system_taxid: 562. Synthetic: yes

NMR struc:

20 models

Authors:

P.Mercier,O.Julien,M.L.Crane,B.D.Sykes

Key ref:

O.Julien et al. (2009). The effect of the cosolvent trifluoroethanol on a tryptophan side chain orientation in the hydrophobic core of troponin C. Protein Sci, 18, 1165-1174. PubMed id: 19472326

Date:

07-Mar-09 Release date: 24-Mar-09

Protein chain

P63316  (TNNC1_HUMAN) -  Troponin C, slow skeletal and cardiac muscles from Homo sapiens

Seq: 161 a.a.

Struc: 89 a.a.*

Protein chain

P19429  (TNNI3_HUMAN) -  Troponin I, cardiac muscle from Homo sapiens

Seq: 210 a.a.

Struc: 20 a.a.

* PDB and UniProt seqs differ at 1 residue position (black cross)

Protein Sci 18:1165-1174 (2009)

PubMed id: 19472326

The effect of the cosolvent trifluoroethanol on a tryptophan side chain orientation in the hydrophobic core of troponin C.

O.Julien, P.Mercier, M.L.Crane, B.D.Sykes.

ABSTRACT

The unique biophysical properties of tryptophan residues have been exploited for decades to monitor protein structure and dynamics using a variety of spectroscopic techniques, such as fluorescence and nuclear magnetic resonance (NMR). We recently designed a tryptophan mutant in the regulatory N-domain of cardiac troponin C (F77W-cNTnC) to study the domain orientation of troponin C in muscle fibers using solid-state NMR. In our previous study, we determined the NMR structure of calcium-saturated mutant F77W-V82A-cNTnC in the presence of 19% 2,2,2-trifluoroethanol (TFE). TFE is a widely used cosolvent in the biophysical characterization of the solution structures of peptides and proteins. It is generally assumed that the structures are unchanged in the presence of cosolvents at relatively low concentrations, and this has been verified for TFE at the level of the overall secondary and tertiary structure for several calcium regulatory proteins. Here, we present the NMR solution structure of the calcium saturated F77W-cNTnC in presence of its biological binding partner troponin I peptide (cTnI(144-163)) and in the absence of TFE. We have also characterized a panel of six F77W-cNTnC structures in the presence and absence TFE, cTnI(144-163), and the extra mutation V82A, and used (19)F NMR to characterize the effect of TFE on the F77(5fW) analog. Our results show that although TFE did not perturb the overall protein structure, TFE did induce a change in the orientation of the indole ring of the buried tryptophan side chain from the anticipated position based upon homology with other proteins, highlighting the potential dangers of the use of cosolvents.