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Title: Evolution of Metal(Loid) Binding Sites in Transcriptional Regulators

Abstract

Expression of the genes for resistance to heavy metals and metalloids is transcriptionally regulated by the toxic ions themselves. Members of the ArsR/SmtB family of small metalloregulatory proteins respond to transition metals, heavy metals, and metalloids, including As(III), Sb(III), Cd(II), Pb(II), Zn(II), Co(II), and Ni(II). These homodimeric repressors bind to DNA in the absence of inducing metal(loid) ion and dissociate from the DNA when inducer is bound. The regulatory sites are often three- or four-coordinate metal binding sites composed of cysteine thiolates. Surprisingly, in two different As(III)-responsive regulators, the metalloid binding sites were in different locations in the repressor, and the Cd(II) binding sites were in two different locations in two Cd(II)-responsive regulators. We hypothesize that ArsR/SmtB repressors have a common backbone structure, that of a winged helix DNA-binding protein, but have considerable plasticity in the location of inducer binding sites. Here we show that an As(III)-responsive member of the family, CgArsR1 from Corynebacterium glutamicum, binds As(III) to a cysteine triad composed of Cys{sup 15}, Cys{sup 16}, and Cys{sup 55}. This binding site is clearly unrelated to the binding sites of other characterized ArsR/SmtB family members. This is consistent with our hypothesis that metal(loid) binding sites in DNA binding proteinsmore » evolve convergently in response to persistent environmental pressures.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
953035
Report Number(s):
SLAC-REPRINT-2009-249
Journal ID: ISSN 0021-9258; JBCHA3; TRN: US200914%%266
DOE Contract Number:  
AC02-76SF00515
Resource Type:
Journal Article
Journal Name:
J. Biol. Chem.283:25706,2008
Additional Journal Information:
Journal Volume: 283; Journal Issue: 37; Journal ID: ISSN 0021-9258
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; CYSTEINE; DNA; GENES; HEAVY METALS; HYPOTHESIS; PLASTICITY; PROTEINS; SEMIMETALS; TRANSITION ELEMENTS; Other,CHEM, BIO

Citation Formats

Ordonez, E, Thiyagarajan, S, Cook, J D, Stemmler, T L, Gil, J A, Mateos, L M, and Rosen, B P. Evolution of Metal(Loid) Binding Sites in Transcriptional Regulators. United States: N. p., 2009. Web.
Ordonez, E, Thiyagarajan, S, Cook, J D, Stemmler, T L, Gil, J A, Mateos, L M, & Rosen, B P. Evolution of Metal(Loid) Binding Sites in Transcriptional Regulators. United States.
Ordonez, E, Thiyagarajan, S, Cook, J D, Stemmler, T L, Gil, J A, Mateos, L M, and Rosen, B P. 2009. "Evolution of Metal(Loid) Binding Sites in Transcriptional Regulators". United States.
@article{osti_953035,
title = {Evolution of Metal(Loid) Binding Sites in Transcriptional Regulators},
author = {Ordonez, E and Thiyagarajan, S and Cook, J D and Stemmler, T L and Gil, J A and Mateos, L M and Rosen, B P},
abstractNote = {Expression of the genes for resistance to heavy metals and metalloids is transcriptionally regulated by the toxic ions themselves. Members of the ArsR/SmtB family of small metalloregulatory proteins respond to transition metals, heavy metals, and metalloids, including As(III), Sb(III), Cd(II), Pb(II), Zn(II), Co(II), and Ni(II). These homodimeric repressors bind to DNA in the absence of inducing metal(loid) ion and dissociate from the DNA when inducer is bound. The regulatory sites are often three- or four-coordinate metal binding sites composed of cysteine thiolates. Surprisingly, in two different As(III)-responsive regulators, the metalloid binding sites were in different locations in the repressor, and the Cd(II) binding sites were in two different locations in two Cd(II)-responsive regulators. We hypothesize that ArsR/SmtB repressors have a common backbone structure, that of a winged helix DNA-binding protein, but have considerable plasticity in the location of inducer binding sites. Here we show that an As(III)-responsive member of the family, CgArsR1 from Corynebacterium glutamicum, binds As(III) to a cysteine triad composed of Cys{sup 15}, Cys{sup 16}, and Cys{sup 55}. This binding site is clearly unrelated to the binding sites of other characterized ArsR/SmtB family members. This is consistent with our hypothesis that metal(loid) binding sites in DNA binding proteins evolve convergently in response to persistent environmental pressures.},
doi = {},
url = {https://www.osti.gov/biblio/953035}, journal = {J. Biol. Chem.283:25706,2008},
issn = {0021-9258},
number = 37,
volume = 283,
place = {United States},
year = {Fri May 22 00:00:00 EDT 2009},
month = {Fri May 22 00:00:00 EDT 2009}
}