Open AccessTrimeric intermediate in the in vivo folding and subunit assembly of the tail spike endorhamnosidase of bacteriophage P22.
Author(s) -
David P. Goldenberg,
Jonathan King
Publication year - 1982
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.79.11.3403
Subject(s) - folding (dsp implementation) , protein subunit , trypsin , chemistry , protein folding , biophysics , biochemistry , crystallography , biology , enzyme , engineering , electrical engineering , gene
Newly synthesized tail spike polypeptide chains mature from trypsin- and NaDodSO4-sensitive unfolded chains to trypsin- and NaDodSO4-resistant native trimers with a t1/2 of 5 min at 30 degrees C. A metastable intermediate in subunit folding and assembly was trapped by chilling and isolated by electrophoresis through nondenaturing gels in the cold. A fraction of the intermediate could be matured into native trimers in vitro by incubating at physiological temperature. Mixing experiments with electrophoretically distinct mutant proteins showed that the precursor that matured in vitro represented three tail spike polypeptide chains already associated with each other but not fully folded. Identification of this intermediate reveals that the processes of polypeptide chain folding and subunit assembly are coupled in this large structural protein.