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Reconstitution of a native‐like SH2 domain from disordered peptide fragments examined by multidimensional heteronuclear NMR
Author(s) -
Ojennus Deanna Dahlke,
Fleissner Mark R.,
Wuttke Deborah S.
Publication year - 2001
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.18701
Subject(s) - heteronuclear single quantum coherence spectroscopy , heteronuclear molecule , chemistry , sh2 domain , peptide , protein structure , non covalent interactions , nuclear magnetic resonance spectroscopy , protein–protein interaction , biophysics , stereochemistry , crystallography , biochemistry , hydrogen bond , biology , proto oncogene tyrosine protein kinase src , molecule , signal transduction , organic chemistry
The N‐terminal SH2 domain from the p85α subunit of phosphatidylinositol 3′ kinase is cleaved specifically into 9‐ and 5‐kD fragments by limited proteolytic digestion with trypsin. The noncovalent SH2 domain complex and its constituent tryptic peptides have been investigated using high‐resolution heteronuclear magnetic resonance (NMR). These studies have established the viability of the SH2 domain as a fragment complementation system. The individual peptide fragments are predominantly unstructured in solution. In contrast, the noncovalent 9‐kD + 5‐kD complex shows a native‐like 1 H‐ 15 N HSQC spectrum, demonstrating that the two fragments fold into a native‐like structure on binding. Chemical shift analysis of the noncovalent complex compared to the native SH2 domain reveals that the highest degree of perturbation in the structure occurs at the cleavage site within a flexible loop and along the hydrophobic interface between the two peptide fragments. Mapping of these chemical shift changes on the structure of the domain reveals changes consistent with the reduction in affinity for the target peptide ligand observed in the noncovalent complex relative to the intact protein. The 5‐kD fragment of the homologous Src protein is incapable of structurally complementing the p85 9‐kD fragment, either in complex formation or in the context of the full‐length protein. These high‐resolution structural studies of the SH2 domain fragment complementation features establish the suitability of the system for further protein‐folding and design studies.