title: Detection of a hidden folding intermediate in the focal adhesion target domain: Implications for its function and folding.
abstract: The focal adhesion target (FAT) domain of focal adhesion kinase has a four-helix bundle structure. Based on a hydrogen exchange-constrained computer simulation study and some indirect experimental results, it has been suggested that a partially unfolded state of the FAT domain with the N-terminal helix unfolded plays an important role in its biological function. Here, using a native-state hydrogen exchange method, we directly detected an intermediate with the N-terminal helix unfolded in a mutant (Y925E) of the FAT domain. In addition, kinetic folding studies on the FAT domain suggest that this intermediate exists on the native side of the rate-limiting transition state for folding. These results provide more direct evidence of the existence of the proposed intermediate and help to understand the folding mechanism of small single domain proteins.
authors.affiliation: Laboratory of Biochemistry, Center for Cancer Research, NCI, NIH, Bethesda, Maryland 20892, USA.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Zhou
authors.forename: Hanqiao
authors.initials: H
authors.lastname: Feng
authors.forename: Yawen
authors.initials: Y
authors.lastname: Bai
mesh_terms: D002942:Circular Dichroism; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D022001:Focal Adhesions / Q000737:chemistry / Q000378:metabolism*; D006859:Hydrogen / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D011489:Protein Denaturation; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D013696:Temperature; D013816:Thermodynamics
chemical_list: D006859:Hydrogen; D051416:Focal Adhesion Protein-Tyrosine Kinases