An intramolecular chaperone inserted in bacteriophage P22 coat protein mediates its chaperonin-independent folding.
The bacteriophage P22 coat protein has the common HK97-like fold but with a genetically inserted domain (I-domain). The role of the I-domain, positioned at the outermost surface of the capsid, is unknown. We hypothesize that the I-domain may act as an intramolecular chaperone because the coat protein folds independently, and many folding mutants are localized to the I-domain. The function of the I-domain was investigated by generating the coat protein core without its I-domain and the isolated I-domain. The core coat protein shows a pronounced folding defect. The isolated I-domain folds autonomously and has a high thermodynamic stability and fast folding kinetics in the presence of a peptidyl prolyl isomerase. Thus, the I-domain provides thermodynamic stability to the full-length coat protein so that it can fold reasonably efficiently while still allowing the HK97-like core to retain the flexibility required for conformational switching during procapsid assembly and maturation.
['Suhanovsky|Margaret M|MM|', 'Teschke|Carolyn M|CM|']
D017100:Bacteriophage P22 D036022:Capsid Proteins D007700:Kinetics D018832:Molecular Chaperones D019696:Peptidylprolyl Isomerase D017510:Protein Folding D055550:Protein Stability D017434:Protein Structure, Tertiary D012486:Salmonella typhimurium
Bacteriophage Protein Folding Protein Self-assembly Protein Stability Virus Assembly