Calcium and lanthanide affinity of the EF-loops from the C-terminal domain of calmodulin

Modulating the affinity and the selectivity of engineered calmodulin EF‐Hand peptides for lanthanides

“…Terbium-binding studies showed that the affinity for the metal ion could be dramatically altered by mutations on either one or more residues of the coordinating loop. The affinities of the peptides presented herein for metal ions are much higher than that reported for other synthetic peptides in aqueous media (Borin et al, 1989;Dadlez et al, 1991;Marsden et al, 1990;Procyshyn and Reid, 1994) and similar or higher than that reported for inserted EF-Hand-binding loop in scaffold proteins (Ye et al, 2005). The introduction of the disulfide bridge, by joining the termini of the binding loop, has greatly lowered the conformational entropic penalty imposed by the metal coordination.…”

“…In aqueous media, they usually have poor affinities for metal cations due to the penalty of conformational entropy. The EF-Hand Ca 2þ -binding loops have also been inserted into other scaffold proteins to gain information about each EF-Hand intrinsic affinity for cations (Ye et al, 2005) but no study on the role of each amino-acid residue was carried out. Recently, we described the synthesis of novel 33 amino-acid long EF-Hand peptides (Le Clainche et al, 2003) corresponding to the first binding site of the calmodulin from paramecium tetraurelia.…”

Identification and Dissection of Ca2+-binding Sites in the Extracellular Domain of Ca2+-sensing Receptor

“…The distances between the two termini of the inserted Ca 2ϩ -binding sites in the model structures of the CaSR were within 15 Å. Accordingly, a total of 5-6 glycine linkers is sufficient to enable the grafted motifs to retain a native metal-binding conformation (48), and two more variants were thus engineered with 3 and 2 flanking Gly residues at the N and C termini of the CaSR sequence. Fig.…”

“…Our laboratory had previously established a grafting approach to investigate the site-specific metal-binding properties of calmodulin (CaM) by inserting the individual EF-loops of CaM into a host frame, CD2 (48). Because predicted Ca 2ϩ -binding sites 1 and 2 of the CaSR have contiguous stretches of amino acids, similar to the Ca 2ϩ -binding motifs in CaM, we extended the grafting approach to probe the site-specific Ca 2ϩ -binding affinity of these two sites.…”

Mastoparan/Mastoparan X altered binding behavior of La3+ to calmodulin in ternary complexes

“…The metal ion dissociation from La 3+ -content ternary complexes was much slower than Ca 2+ -CaM-Mas complexes [6,17]; but La 3+ -content CaM complexes exhibit significantly reduced CaN activation [7]. In addition to the biological interest, the CaM metal binding properties have also made it an attractive target for protein engineering [18][19][20][21].…”