PDBsum entry 1la0

Contractile protein

PDB id: 1la0

Contents

Protein chain

161 a.a. *

Metals

_CA ×3

* Residue conservation analysis

PDB id:

1la0

Name:

Contractile protein

Title:

Solution structure of calcium saturated cardiac troponin c in the troponin c-troponin i complex

Structure:

Troponin c, slow skeletal and cardiac muscles. Chain: a. Synonym: tn-c. Engineered: yes

Source:

Gallus gallus. Chicken. Organism_taxid: 9031. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

NMR struc:

1 models

Authors:

A.Dvoretsky,E.M.Abusamhadneh,J.W.Howarth,P.R.Rosevear

Key ref:

A.Dvoretsky et al. (2002). Solution structure of calcium-saturated cardiac troponin C bound to cardiac troponin I. J Biol Chem, 277, 38565-38570. PubMed id: 12147696 DOI: 10.1074/jbc.M205306200

Date:

27-Mar-02 Release date: 11-Dec-02

Protein chain

P09860  (TNNC1_CHICK) -  Troponin C, slow skeletal and cardiac muscles from Gallus gallus

Seq: 161 a.a.

Struc: 161 a.a.

DOI no: 10.1074/jbc.M205306200

J Biol Chem 277:38565-38570 (2002)

PubMed id: 12147696

Solution structure of calcium-saturated cardiac troponin C bound to cardiac troponin I.

A.Dvoretsky, E.M.Abusamhadneh, J.W.Howarth, P.R.Rosevear.

ABSTRACT

Cardiac troponin C (TnC) is composed of two globular domains connected by a flexible linker. In solution, linker flexibility results in an ill defined orientation of the two globular domains relative to one another. We have previously shown a decrease in linker flexibility in response to cardiac troponin I (cTnI) binding. To investigate the relative orientation of calcium-saturated TnC domains when bound to cTnI, (1)H-(15)N residual dipolar couplings were measured in two different alignment media. Similarity in alignment tensor orientation for the two TnC domains supports restriction of domain motion in the presence of cTnI. The relative spatial orientation of TnC domains bound to TnI was calculated from measured residual dipolar couplings and long-range distance restraints utilizing a rigid body molecular dynamics protocol. The relative domain orientation is such that hydrophobic pockets face each other, forming a latch to constrain separate helical segments of TnI. We have utilized this structure to successfully explain the observed functional consequences of linker region deletion mutants. Together, these studies suggest that, although linker plasticity is important, the ability of TnC to function in muscle contraction can be correlated with a preferred domain orientation and interdomain distance.

Selected figure(s)

Figure 2.
Fig. 2. Surface representation of Ca^2+-saturated cTnC bound to cTnI. Hydrophobic surface area is shown in yellow. The cTnI regulatory and N-terminal domain helices are shown in magenta and blue, respectively. cTnI peptides were modeled using the structures of cTnC-(1-89) bound to cTnI-(147-163) (Protein Data Bank code 1MXL) and sTnC bound to sTnI-(1-47) (Protein Data Bank code 1A2X). Views A and B are related by a 90° rotation.

Figure 3.
Fig. 3. Surface representations of EF-hand protein-target interactions. A, the solution structure of cTnC bound to cTnI . cTnC was found to have bend, azimuth, and twist angles of 70°, 30°, and 29°, respectively. B, the x-ray structure of sTnC bound to sTnI-(1-47) (11). The orientation of sTnC domains is defined by bend, azimuth, and twist angles of 93°, 162°, and 25°, respectively. C, the crystal structure of four Ca^2+-loaded sTnC (36). The orientation of sTnC domains is defined by bend, azimuth, and twist angles of 12°, 94°, and 3°, respectively. The N- and C-terminal domains of TnC are shown in gold and red, respectively. TnI peptides are shown in magenta and blue. Superposition of TnC C-terminal domains was used to provide similar orientations. D, the NMR structure of Ca^2+-bound CaM complexed with the myosin light chain kinase peptide (37). The orientation of CaM domains is defined by bend, azimuth, and twist angles of 111°, 95°, and 68°, respectively. The N- and C-terminal domains of CaM are shown in gold and red, respectively. The CaM-bound myosin light chain kinase peptide is shown in blue. Superposition of the CaM C-terminal domain and the TnC C-terminal domain was used to provide similar orientations.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2002, 277, 38565-38570) copyright 2002.

Figures were selected by an automated process.