Stabilization of the alpha-helical coiled-coil domain in laminin by C-terminal disulfide bonds.


Abstract

The long arm of laminin in which three polypeptide chains alpha, beta, and gamma are assembled in an alpha-helical coiled-coil structure is stabilized by non-covalent interactions and disulfide bridges. The stabilizing role of the disulfide linkage between the beta and gamma-chains at the C-terminal region of the assembly domain was investigated with about 100-residue long recombinant fragments. Circular dichroism spectra and electron micrographs were identical for linked and non-linked species and indicated two-stranded coiled-coil structures with about 100% alpha-helicity at 20 degrees C. Thermal transition profiles revealed an increase of the melting temperature from 42 degrees C to 60.4 degrees C upon disulfide formation at a chain concentration of 25 microM. The enthalpy of interaction was identical for the two species but the negative entropy involved in joining the two chains was reduced by the disulfide bonds. At chain concentrations of 10 microM the Gibbs free energy delta G was by 17.5 kJ/mol more negative for the disulfide-linked than for the unlinked chains. Because of the concentration dependence of the entropy of the non-linked chains, this difference decreased with increasing concentration and, by extrapolation at chain concentrations of 10 mM, the stability of both structures would be the same. As a competing reaction, beta-chains associated to four-stranded bundles which probably consist of pairs of two-stranded coiled-coils. After disulfide formation a biphasic transition curve was observed which indicated two different ways of connecting the chains in the bundle. Study holds ProTherm entries: 7491, 7492 Extra Details: laminin; alpha-helical coiled-coil; recombinant fragments;,disulfide linkage; circular dichroism

Submission Details

ID: biNY4rLe

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:34 p.m.

Version: 1

Publication Details
Antonsson P;Kammerer RA;Schulthess T;Hänisch G;Engel J,J. Mol. Biol. (1995) Stabilization of the alpha-helical coiled-coil domain in laminin by C-terminal disulfide bonds. PMID:7602598
Additional Information

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P
 

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)


Relevant PDB Entries

Structure ID Release Date Resolution Structure Title
5IK4 2016-08-10 1.27 Laminin A2LG45 C-form, Apo.
5IK5 2016-08-10 1.39 Laminin A2LG45 C-form, G6/7 bound.
5IK8 2016-08-10 2.0 Laminin A2LG45 I-form, G6/7 bound.
1DYK 2001-02-04 2.0 Laminin alpha 2 chain LG4-5 domain pair
5IK7 2016-08-10 2.0 Laminin A2LG45 I-form, Apo.
1QU0 1999-12-03 2.35 CRYSTAL STRUCTURE OF THE FIFTH LAMININ G-LIKE MODULE OF THE MOUSE LAMININ ALPHA2 CHAIN
1OKQ 2003-09-11 2.8 LAMININ ALPHA 2 CHAIN LG4-5 DOMAIN PAIR, CA1 SITE MUTANT
2WJS 2009-06-23 2.8 Crystal structure of the LG1-3 region of the laminin alpha2 chain

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Laminin subunit alpha-2 Q60675 LAMA2_MOUSE