Stability of wild-type and temperature-sensitive protein subunits of the phage P22 capsid.


Abstract

Temperature-sensitive folding (tsf) mutants of the phage P22 coat protein prevent newly synthesized polypeptide chains from reaching the conformation competent for capsid assembly in cells, and can be rescued by the GroEL chaperone (Gordon, C., Sather, S., Casjens, S., and King, J. (1994) J. Biol. Chem. 269, 27941-27951). Here we investigate the stabilities of wild-type and four tsf mutant unpolymerized subunits. Wild-type coat protein subunits denatured at 40 degrees C, with a calorimetric enthalpy of approximately 600 kJ/mol. Comparison with coat protein denaturation within the shell lattice (Tm = 87 degrees C, delta H approximately 1700 kJ/mol) (Galisteo, M.L., and King, J. (1993) Biophys. J. 65, 227-235) indicates that protein-protein interactions within the capsid provide enormous stabilization. The melting temperatures of the subunits carrying tsf substitutions were similar to wild-type. At low temperatures, the tsf mutants, but not the wild-type, formed non-covalent dimers, which were dissociated at temperatures above 30 degrees C. Spectroscopic and calorimetric studies indicated that the mutant proteins have reduced amounts of ordered structure at low temperature, as compared to the wild-type protein. Although complex, the in vitro phenotypes are consistent with the in vivo finding that the mutants are defective in folding, rather than subunit stability. These results suggest a role for incompletely folded subunits as precursors in viral capsid assembly, providing a mechanism of reaching multiple conformations in the polymerized form. Study holds ProTherm entries: 5167, 5168, 5169, 5170, 5171 Extra Details:

Submission Details

ID: 7TonqtPM3

Submitter: Connie Wang

Submission Date: April 24, 2018, 8:28 p.m.

Version: 1

Publication Details
Galisteo ML;Gordon CL;King J,J. Biol. Chem. (1995) Stability of wild-type and temperature-sensitive protein subunits of the phage P22 capsid. PMID:7622466
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
2M5S 2014-03-05 High-resolution NMR structure and cryo-EM imaging support multiple functional roles for the accessory I-domain of phage P22 coat protein
5UU5 2017-03-15 3.3 Bacteriophage P22 mature virion capsid protein
2XYY 2011-02-02 3.8 De Novo model of Bacteriophage P22 procapsid coat protein
2XYZ 2011-02-02 4.0 De Novo model of Bacteriophage P22 virion coat protein
3IYH 2010-03-31 8.2 P22 procapsid coat protein structures reveal a novel mechanism for capsid maturation: Stability without auxiliary proteins or chemical cross-links
3IYI 2010-03-31 9.1 P22 expanded head coat protein structures reveal a novel mechanism for capsid maturation: Stability without auxiliary proteins or chemical cross-links

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
100.0 Major capsid protein P26747 CAPSD_BPP22