Open AccessStructural requirements for thymosin β4 in its contact with actin
Author(s) -
Simenel Catherine,
Van Troys Marleen,
Vandekerckhove Joël,
Ampe Christophe,
Delepierre Muriel
Publication year - 2000
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.2000.01380.x
Subject(s) - helix (gastropod) , thymosin , chemistry , alpha helix , stereochemistry , residue (chemistry) , protein structure , nuclear magnetic resonance spectroscopy , triple helix , alanine , circular dichroism , mutant , biophysics , lysine , crystallography , biochemistry , amino acid , biology , ecology , snail , gene
We examined the conformational preferences of mutants of thymosin β4, an actin monomer sequestering protein by NMR spectroscopy in 60% (v/v) trifluoroethanol. Under these conditions, the wild‐type thymosin β4 conformation consists of an α‐helix (helix I) extending from residues 5–16 with a more stable fragment from lysine 11 to lysine 16 and a second α‐helix (helix II) encompassing residues 31–39. The point mutations studied here are located in helix I or in the LKKTET segment (residues 17–22) that form the two main entities of interaction with the actin molecule. The α‐ 1 H conformational shifts allow us to investigate the helicity of the polypeptides at the residue level and to correlate these structures with their biological activity. We determine that an extension of helix I at its C‐terminal end over the LKK‐segment results in loss of activity. The correct termination of this helix is connected to a specific orientation of the polypeptide essential for a cooperative action of the thymosin β4 binding entities required for full activity.