Effects of cavity-creating mutations on conformational stability and structure of the dimeric 4-alpha-helical protein ROP: thermal unfolding studies.


Abstract

The structural and energetic perturbations caused by cavity-creating mutations (Leu-41-->Val and Leu-41-->Ala) in the dimeric 4-alpha-helical-bundle protein ROP have been characterized by CD spectroscopy and differential scanning calorimetry (DSC). Deconvolution of the CD spectra showed a decrease in alpha-helicity as a result of the amino acid exchanges that follows qualitatively the overall decrease in conformational stability. Transition enthalpies are sensitive probes of the energetic change associated with point mutations. delta H zero values at the respective transition temperatures, T 1/2 (71.0, 65.3, and 52.9 degrees C at 0.5 mg/ml) decrease from 580 +/- 20 to 461 +/- 20 kJ/(mol of dimer) and 335 +/- 20 kJ/(mol of dimer) for wild-type ROP (Steif, C., Weber, P., Hinz, H.-J., Flossdorf, J., Cesareni, G., Kokkinidis, M. Biochemistry 32:3867-3876, 1993), L41V, and L41A, respectively. The conformational stabilities at 25 degrees C expressed by the standard Gibbs energies of denaturation, delta GzeroD, are 71.7, 61.1, and 46.1 kJ/(mol of dimer). The corresponding transition enthalpies have been obtained from extrapolation using the cDp(T) and cNp(T) functions. Their values at 25 degrees C are 176.3, 101.9, and 141.7 kJ/(mol of dimer) for wild-type ROP, L41V, and L41A, respectively. When the stability perturbation resulting from the cavity creating mutations is referred to the exchange of 1 mol of CH2 group, the average delta delta GzeroD value is -5.0 +/- 1 kJ/(mol of CH2 group). This decrease in conformation stability suggests that dimeric ROP exhibits the same susceptibility to Leu-->Val and Leu-->Ala exchanges as small monomeric proteins. Careful determinations of the partial specific heat capacities of wild-type and mutated protein solutions suggest that the mutational effects are predominantly manifested in the native rather than the unfolded state. Study holds ProTherm entries: 3104, 3105, 3106, 11859, 11860, 11861 Extra Details: additive : EDTA(1 mM) protein stability; 4-alpha-helix bundle; ROP protein;,cavity mutations; heat capacity

Submission Details

ID: Bh5Wk7Jr3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:21 p.m.

Version: 1

Publication Details
Steif C;Hinz HJ;Cesareni G,Proteins (1995) Effects of cavity-creating mutations on conformational stability and structure of the dimeric 4-alpha-helical protein ROP: thermal unfolding studies. PMID:8539253
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
1RPR 1994-01-31 THE STRUCTURE OF COLE1 ROP IN SOLUTION
1NKD 1999-03-23 1.09 ATOMIC RESOLUTION (1.07 ANGSTROMS) STRUCTURE OF THE ROP MUTANT <2AA>
4DO2 2013-02-13 1.4 Crystal Structure of the Rop protein mutant D30P/A31G at resolution 1.4 resolution.
1RPO 1995-02-14 1.4 RESTORED HEPTAD PATTERN CONTINUITY DOES NOT ALTER THE FOLDING OF A 4-ALPHA-HELICAL BUNDLE
2IJK 2007-10-16 1.55 Structure of a Rom protein dimer at 1.55 angstrom resolution
1ROP 1992-07-15 1.7 STRUCTURE OF THE COL*E1 ROP PROTEIN AT 1.7 ANGSTROMS RESOLUTION
2IJH 2007-10-16 1.8 Crystal structure analysis of ColE1 ROM mutant F14W
1B6Q 1999-07-09 1.8 ALANINE 31 PROLINE MUTANT OF ROP PROTEIN
1GTO 1997-01-27 1.82 HIGH RESOLUTION STRUCTURE OF A HYPERSTABLE HELICAL BUNDLE PROTEIN MUTANT
2IJJ 2007-10-16 1.9 Crystal structure analysis of ColE1 ROM mutant F14Y
1GMG 2002-09-12 1.9 ALANINE 31 PROLINE MUTANT OF ROP PROTEIN, MONOCLINIC FORM
1F4N 2001-01-10 1.9 C2 CRYSTAL STRUCTURE OF ALA2ILE2-6, A VERSION OF ROP WITH A REPACKED HYDROPHOBIC CORE AND A NEW FOLD.
3K79 2010-02-02 1.96 C38A, C52V Cysteine-Free Variant of Rop (Rom)
1QX8 2004-09-28 2.02 Crystal structure of a five-residue deletion mutant of the Rop protein
1F4M 2001-01-10 2.25 P3(2) CRYSTAL STRUCTURE OF ALA2ILE2-6, A VERSION OF ROP WITH A REPACKED HYDROPHOBIC CORE AND A NEW FOLD.
2IJI 2007-10-16 2.3 Structure of F14H mutant of ColE1 Rom protein
2GHY 2006-05-30 2.5 Novel Crystal Form of the ColE1 Rom Protein
1YO7 2005-02-15 2.8 Re-engineering topology of the homodimeric ROP protein into a single-chain 4-helix bundle

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Regulatory protein rop P03051 ROP_ECOLX