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The dimerization domain of the HIV‐1 capsid protein binds a capsid protein‐derived peptide: A biophysical characterization
Author(s) -
Garzón María T.,
LidónMoya María C.,
Barrera Francisco N.,
Prieto Alicia,
Gómez Javier,
Mateu Mauricio G.,
Neira José L.
Publication year - 2004
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.03555304
Subject(s) - capsid , dissociation constant , chemistry , circular dichroism , isothermal titration calorimetry , peptide , crystallography , dissociation (chemistry) , biophysics , binding constant , stereochemistry , binding site , biochemistry , biology , gene , receptor
The type 1 HIV presents a conical capsid formed by ∼1500 units of the capsid protein, CA. Homodimer‐ization of CA via its C‐terminal domain, CA‐C, constitutes a key step in virion assembly. CA‐C dimerization is largely mediated by reciprocal interactions between residues of its second α‐helix. Here, we show that an N‐terminal‐acetylated and C‐terminal–amidated peptide, CAC1, comprising the sequence of the CA‐C dimerization helix plus three flanking residues at each side, is able to form a complex with the entire CA‐C domain. Thermal denaturation measurements followed by circular dichroism (CD), NMR, and size‐exclusion chromatography provided evidence of the interaction between CAC1 and CA‐C. The apparent dissociation constant of the heterocomplex formed by CA‐C and CAC1 was determined by several biophysical techniques, namely, fluorescence (using an anthraniloyl‐labeled peptide), affinity chromatography, and isothermal titration calorimetry. The three techniques yielded similar values for the apparent dissociation constant, in the order of 50 μM. This apparent dissociation constant was only five times higher than was the dissociation constant of both CA‐C and the intact capsid protein homodimers (10 μM).