Thermodynamic analysis of the structural stability of phage 434 Cro protein.


Thermodynamic parameters describing the phage 434 Cro protein have been determined by calorimetry and, independently, by far-UV circular dichroism (CD) measurements of isothermal urea denaturations and thermal denaturations at fixed urea concentrations. These equilibrium unfolding transitions are adequately described by the two-state model. The far-UV CD denaturation data yield average temperature-independent values of 0.99 +/- 0.10 kcal mol(-)(1) M(-)(1) for m and 0.98 +/- 0.05 kcal mol(-)(1) K(-)(1) for DeltaC(p)()(,U), the heat capacity change accompanying unfolding. Calorimetric data yield a temperature-independent DeltaC(p)()(,U) of 0.95 +/- 0.30 kcal mol(-)(1) K(-)(1) or a temperature-dependent value of 1.00 +/- 0.10 kcal mol(-)(1) K(-)(1) at 25 degrees C. DeltaC(p)()(,U) and m determined for 434 Cro are in accord with values predicted using known empirical correlations with structure. The free energy of unfolding is pH-dependent, and the protein is completely unfolded at pH 2.0 and 25 degrees C as judged by calorimetry or CD. The stability of 434 Cro is lower than those observed for the structurally similar N-terminal domain of the repressor of phage 434 (R1-69) or of phage lambda (lambda(6)(-)(85)), but is close to the value reported for the putative monomeric lambda Cro. Since a protein's structural stability is important in determining its intracellular stability and turnover, the stability of Cro relative to the repressor could be a key component of the regulatory circuit controlling the levels and, consequently, the functions of the two proteins in vivo. Study holds ProTherm entries: 5682, 5683, 5684, 5685, 5686, 5687, 5688, 5689, 5690, 5691 Extra Details: equilibrium unfolding transition; free energies of unfolding;,intracellular stability; regulatory circuit

Submission Details

ID: qdfeeKVy

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:30 p.m.

Version: 1

Publication Details
Padmanabhan S;Laurents DV;Fernández AM;Elias-Arnanz M;Ruiz-Sanz J;Mateo PL;Rico M;Filimonov VV,Biochemistry (1999) Thermodynamic analysis of the structural stability of phage 434 Cro protein. PMID:10569937
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
1ZUG 1997-03-14T00:00:00+0000 0 STRUCTURE OF PHAGE 434 CRO PROTEIN, NMR, 20 STRUCTURES
3CRO 1990-07-06T00:00:00+0000 2.5 THE PHAGE 434 CRO/OR1 COMPLEX AT 2.5 ANGSTROMS RESOLUTION

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Regulatory protein cro P03036 RCRO_BP434