Differences in the conformational state of a zinc-finger DNA-binding protein domain occupied by zinc and copper revealed by electrospray ionization mass spectrometry

摘要: Transition metal ions are important in biological regulation partly because they can bind to and stabilize protein surface domain structures specific conformations that involved key molecular recognition events. There twso C2-C2 type zinc-finger sequences within the highly conserved DNA-binding of estrogen receptor (ERDBD). Electrospray ionization (ESI) mass spectrometry has been used demonstrate metal-binding sites 71-residue ERDBD either Zn (up 2) or Cu 4). Evidence for induction /or stabilization a different conformational state with bound is revealed by characteristic shift ESI charge envelope. The 10+ most abundant fully reduced apopeptide ERDBD-Zn holopeptide (bound does not alter In contrast, 8+ typically optimjum observed ERDBD-Cu holopeptide; indeed, entire envelope frame-shifted lower states Cu. Interpretation altered simplified (i) single ligand (sulfur) case both binding, (ii) two cations divaalent. Thus, it likely dissimilar envelopes represent peptide conformers, each which stabilized ion. covalent bridging adjacent Cys residues similar formation intramolecular disulfide bonds, process we also found decrease optimum mumber ESI. existence distinct consistent differences apparent coordinate geometry stoichiometry ions. Our findings aslo prevous investigations globular proteins reveal an increase number when structure disrupted reduction bonds.