The actin binding site of thymosin beta 4 mapped by mutational analysis.

We characterized in detail the actin binding site of the small actin-sequestering protein thymosin beta 4 (T beta 4) using chemically synthesized full-length T beta 4 variants. The N-terminal part (residues 1-16) and a hexapeptide motif (residues 17-22) form separate structural entities. In both, we identified charged and hydrophobic residues ...
that participate in the actin interaction using chemical cross-linking, complex formation in native gels and actin-sequestering experiments. Quantitative data on the activity of the variants and circular dichroism experiments allow to present a model in which the N-terminal part needs to adopt an alpha-helix for actin binding and interacts through a patch of hydrophobic residues (6M-I-F12) on one side of this helix. Also, electrostatic contacts between actin and lysine residues 18, in the motif, and 14, in the N-terminal alpha-helix, appear important for binding. The residues critical for contacting actin are conserved throughout the beta-thymosin family and in addition to this we identify a similar pattern in the C-terminal headpiece of villin and dematin.
Mesh Terms:
Actins, Amino Acid Sequence, Animals, Binding Sites, Binding, Competitive, Blood Proteins, Calcium-Binding Proteins, Carrier Proteins, Chickens, Circular Dichroism, Conserved Sequence, Cross-Linking Reagents, Genetic Variation, Humans, Kinetics, Membrane Proteins, Microfilament Proteins, Molecular Sequence Data, Muscle, Skeletal, Mutagenesis, Site-Directed, Peptide Fragments, Phosphoproteins, Protein Structure, Secondary, Rabbits, Recombinant Proteins, Sequence Homology, Amino Acid, Thymosin
EMBO J.
Date: Jan. 15, 1996
Download Curated Data For This Publication
53
Switch View:
  • Interactions 1