Sunday, October 16, 2011

Single-molecule fluorescence spectroscopy maps the folding landscape of a large protein


  • Menahem Pirchi,
  • Guy Ziv,
  • Inbal Riven,
  • Sharona Sedghani Cohen,
  • Nir Zohar,
  • Yoav Barak, and
  •  Gilad Haran
  • Proteins attain their function only after folding into a highly organized three-dimensional structure. Much remains to be learned about the mechanisms of folding of large multidomain proteins, which may populate metastable intermediate states on their energy landscapes. Here we introduce a novel method, based on high-throughput single-molecule fluorescence experiments, which is specifically geared towards tracing the dynamics of folding in the presence of a plethora of intermediates. We employ this method to characterize the folding reaction of a three-domain protein, adenylate kinase. Using thousands of single-molecule trajectories and hidden Markov modelling, we identify six metastable states on adenylate kinase's folding landscape. Remarkably, the connectivity of the intermediates depends on denaturant concentration; at low concentration, multiple intersecting folding pathways co-exist. We anticipate that the methodology introduced here will find broad applicability in the study of folding of large proteins, and will provide a more realistic scenario of their conformational dynamics.
  • Journal: Nature Communications

No comments:

Post a Comment