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Influence of the N Terminus and the Actin‐Binding Motif of Thymosin β 4 on Its Interaction with G‐Actin
Author(s) -
ZOUBEK ROBERT E.,
HANNAPPEL EWALD
Publication year - 2007
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1415.026
Subject(s) - thymosin , actin , acetylation , biochemistry , amino acid , biology , actin binding protein , actina , plasma protein binding , chemistry , binding site , microbiology and biotechnology , cytoskeleton , actin cytoskeleton , gene , cell
: Thymosin β 4 binds G‐actin in a 1:1 ratio and prevents its aggregation to F‐actin by sequestration. Substitution or modification of single amino acid residues within the N‐terminal sequence 1 to 22 of thymosin β 4 alters its interaction with G‐actin.We generated thymosin β 4 variants with amino acid substitutions within the N‐terminal α‐helix and the putative actin‐binding motif. None of the E. coli‐ generated thymosin β 4 variants was modified or acetylated at its N terminus. The stability of the complex of G‐actin with nonacetylated thymosin β 4 or β 4 A7V is higher than the one with naturally occurring thymosin β 4 , which is always acetylated. The complex of G‐actin with nonacetylated thymosin β 4 A7V,K18,19A and β 4 K14,16,18,19A is 15 times less stable compared to the complex with thymosin β 4 . The G‐actin sequestering activities of all thymosin β 4 variants correspond to their complex stabilities with G‐actin, except for nonacetylated thymosin β 4 A7V , where it is attenuated. Thymosin β 4 Δ17–23 missing the putative actin‐binding motif shows no interaction with G‐actin.