Metal-binding properties of a dicysteine-containing motif in protein tyrosine kinases

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Studying the structural consequences of the direct binding of arsenite, cadmium, cobalt, nickel, and lead to a number of protein tyrosine kinases led to the discovery of the metal-binding properties of a dicysteine-containing motif in the C-terminal (CT) lobe of the kinases. Of all the synthesized peptides derived from different domains of c-Src and Csk, only peptides based on a dicysteine-containing motif located in the CT lobe of the kinase domain - CPESLHDLMCQC and CPESLHDLMC in c-Src, and CPPA-VYDVMKNC in Csk - exhibited significant conformational changes in the presence of all metals, as shown by circular dichroism (CD) analyses. Furthermore, CD analysis of natural enzymes c-Src, Csk, Fyn, c-Abl, Lck, EGFR, and c-Src domains containing the CT lobe in the presence of metals showed a significant concentration-dependent conformational change. ICP-MS, 113Cd NMR, 33S NMR, and/or molecular modeling studies of CPESLHDLMC and CPPA-VYDVMKNC confirmed the binding between the free sulfhydryl groups of the cysteine residues and CdII or AsIII. UV-titration studies suggested a high-affinity interaction between CdII and AsIII and the peptides (Kd, values in the range of 0.6-18.3 nm). © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.

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