title: An intramolecular chaperone inserted in bacteriophage P22 coat protein mediates its chaperonin-independent folding.
abstract: 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.
authors.affiliation: Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269.
authors.forename: Margaret M
authors.initials: MM
authors.lastname: Suhanovsky
authors.affiliation: Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269; Department of Chemistry, University of Connecticut, Storrs, Connecticut 06269. Electronic address: teschke@uconn.edu.
authors.forename: Carolyn M
authors.initials: CM
authors.lastname: Teschke
mesh_terms: D017100:Bacteriophage P22 / Q000235:genetics / Q000378:metabolism*; D036022:Capsid Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D007700:Kinetics; D018832:Molecular Chaperones / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D019696:Peptidylprolyl Isomerase / Q000737:chemistry; D017510:Protein Folding; D055550:Protein Stability; D017434:Protein Structure, Tertiary; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism / Q000821:virology
chemical_list: D036022:Capsid Proteins; D018832:Molecular Chaperones; D019696:Peptidylprolyl Isomerase
keywords: Bacteriophage; Protein Folding; Protein Self-assembly; Protein Stability; Virus Assembly