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M9620661.TXT
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1996-02-26
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Document 0661
DOCN M9620661
TI A single amino acid in the SH3 domain of Hck determines its high
affinity and specificity in binding to HIV-1 Nef protein.
DT 9602
AU Lee CH; Leung B; Lemmon MA; Zheng J; Cowburn D; Kuriyan J; Saksela K;
Laboratory of Molecular Biophysics, Rockefeller University, New; York,
NY 10021, USA.
SO EMBO J. 1995 Oct 16;14(20):5006-15. Unique Identifier : AIDSLINE
MED/96067129
AB We have examined the differential binding of Hck and Fyn to HIV-1 Nef to
elucidate the structural basis of SH3 binding affinity and specificity.
Full-length Nef bound to Hck SH3 with the highest affinity reported for
an SH3-mediated interaction (KD 250 nM). In contrast to Hck, affinity of
the highly homologous Fyn SH3 for Nef was too weak (KD > 20 microM) to
be accurately determined. We show that this distinct specificity lies in
a variable loop, the 'RT loop', positioned close to conserved SH3
residues implicated in the binding of proline-rich (PxxP) motifs. A
mutant Fyn SH3 with a single amino acid substitution (R96I) in its RT
loop had an affinity (KD 380 nM) for Nef comparable with that of Hck
SH3. Based on additional mutagenesis studies we propose that the
selective recognition of Nef by Hck SH3 is determined by hydrophobic
interactions involving an isoleucine residue in its RT loop. Although
Nef contains a PxxP motif which is necessary for the interaction with
Hck SH3, high affinity binding was only observed for intact Nef protein.
The binding of a peptide containing the Nef PxxP motif showed > 300-fold
weaker affinity for Hck SH3 than full-length Nef.
DE *src Homology Domains Amino Acid Sequence Biosensors Calorimetry
Circular Dichroism Comparative Study Gene Products,
nef/GENETICS/*METABOLISM HIV-1/GENETICS/*METABOLISM Models, Molecular
Molecular Sequence Data Oligopeptides/CHEMICAL SYNTHESIS Precipitation
Protein Binding Protein Conformation Protein-Tyrosine
Kinase/GENETICS/*METABOLISM Proto-Oncogene
Proteins/GENETICS/*METABOLISM Recombinant Proteins/METABOLISM Sequence
Homology, Amino Acid Spectrometry, Fluorescence Structure-Activity
Relationship Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Time
Factors JOURNAL ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).