A Novel Cysteine Cluster in Human Metal-responsive Transcription Factor 1 Is Required for Heavy Metal-induced Transcriptional Activation in Vivo * Academic Article uri icon

abstract

  • Metal-responsive transcription factor 1 (MTF-1) specifically binds to metal response elements (MREs) associated with a number of metal- and stress-responsive genes. Human MTF-1 contains a cysteine-rich cluster, -632Cys-Gln-Cys-Gln-Cys-Ala-Cys638-, conserved from pufferfish to humans far removed from the MRE-binding zinc finger domain and just C-terminal to a previously mapped serine/threonine-rich transcriptional activation domain. MTF-1 proteins containing two Cys-->Ala substitutions (C632A/C634A) or a deletion in this region altogether (Delta(632-644)) are significantly impaired in their ability to induce Zn(II)- and Cd(II)-responsive transcription of a MRE-linked reporter gene in transiently transfected mouse dko7 (MTF-1-/-) cells in culture under moderate metal stress but retain the ability to drive basal levels of transcription in a MRE-dependent manner in vivo and in vitro. In addition, the mutated proteins respond to induction by Zn(II) or Cd(II) with nuclear translocation and MRE binding activities comparable with wild-type MTF-1. Attempts to rescue the Delta(632-644) deletion mutant phenotype by inserting similar Cys-rich sequences from Drosophila MTF-1 were unsuccessful, suggesting that the structure of this motif within intact human MTF-1, rather than the simple presence of multiple closely spaced Cys residues, is required for function. This cysteine cluster therefore functions at a step subsequent to nuclear translocation and MRE-binding DNA to naked promoter-containing DNA and appears to be specifically required for MTF-1 to activate transcription in the presence of inducing heavy metal ions.

altmetric score

  • 3

author list (cited authors)

  • Chen, X., Zhang, B. o., Harmon, P. M., Schaffner, W., Peterson, D. O., & Giedroc, D. P.

citation count

  • 44

complete list of authors

  • Chen, Xiaohua||Zhang, Bo||Harmon, Philip M||Schaffner, Walter||Peterson, David O||Giedroc, David P

publication date

  • November 2003