Site selection in tandem arrays of metal-binding domains.
The metal binding properties of peptides corresponding to metal-binding sites spanning regions that normally function as linkers in tandem arrays of metal-binding domain-containing proteins were examined. For a peptide with two His residues from one TFIIIA-like zinc finger domain, a canonical TFIIIA-like linker, and two Cys residues from an adjacent zinc domain, the dissociation constant for the 1:1 peptide to cobalt(II) was found to be 15 +/- 10 microM, compared with 60 nM for the corresponding zinc finger domains themselves. Peptides overlapping two sets of metal-binding domains from human TRAF (tumor necrosis factor receptor-associated factor) proteins were examined. In one case, the affinity of the presumed metal-binding domain and that for the linker region were comparable, while in the second case, the affinity of the linker peptide was higher than that for the corresponding presumed metal-binding domain peptide. These studies revealed that cobalt(II) affinities in the micromolar range can occur even for peptides that do not correspond to natural zinc-binding domains and that the degree of distinction between authentic metal-binding domains and the corresponding linker-spanning peptides may be modest, at least for single domain peptide models.
Thickman
Karen R
KR
Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Davis
Alisa
A
Berg
Jeremy M
JM
D000595:Amino Acid Sequence; D001665:Binding Sites; D008670:Metals / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D035582:Transcription Factor TFIIIA / Q000737:chemistry; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins / Q000737:chemistry; D016335:Zinc Fingers / Q000235:genetics
D008670:Metals; D010455:Peptides; D035582:Transcription Factor TFIIIA; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins