title: Mastoparan/Mastoparan X altered binding behavior of La3+ to calmodulin in ternary complexes.
abstract: Ca(2+) binds to calmodulin (CaM) and triggers the interaction of CaM with its target proteins; CaM binding proteins (CaMBPs) can also regulate the metal binding to CaM. In the present paper, La(3+) binding to CaM was studied in the presence of the CaM binding peptides, Mastoparan (Mas) and Mas X, using ultrafiltration and titration of fluorescence. Ca(2+) binding was used as an analog to understand La(3+) binding in intact CaM and isolated N/C-terminal CaM domain of metal-CaM binary system and metal-CaM-CaMBPs ternary system. Mas/Mas X increased binding affinity of La(3+) to CaM by 0.5 approximately 3 orders magnitude. The metal ions binding affinity to the C-terminal or the N-terminal CaM domain suggested that in the first phase of binding process both Ca(2+) and La(3+) bind to C-terminal of CaM in the presence of Mas/Mas X. In the presence of CaM binding peptides, La(3+) binding preference was substantially altered from the metal-CaM binary system where La(3+) slightly preferred binding to the N-terminal sites of CaM. Our results will be helpful in understanding La(3+) interactions with CaM in the biological systems.
authors.affiliation: Department of Chemical Biology and State Key Laboratories of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100083, PR China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Yang
authors.forename: Jian
authors.initials: J
authors.lastname: Hu
authors.forename: Xiaoda
authors.initials: X
authors.lastname: Yang
authors.forename: Kui
authors.initials: K
authors.lastname: Wang
mesh_terms: D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000737:chemistry / Q000378:metabolism*; D002148:Calmodulin-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D007811:Lanthanum / Q000737:chemistry / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D014862:Wasp Venoms / Q000737:chemistry / Q000378:metabolism*
chemical_list: D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D014862:Wasp Venoms; D007811:Lanthanum; C037500:mastoparan; C071123:mastoparan X; D002118:Calcium