The E. coli hicAB type II toxin-antitoxin locus is unusual by being controlled by two promoters and by having the toxin encoded upstream of the antitoxin. HicA toxins contain a double-stranded RNA-binding fold and cleaves both mRNA and tmRNA in vivo, ...
The E. coli hicAB type II toxin-antitoxin locus is unusual by being controlled by two promoters and by having the toxin encoded upstream of the antitoxin. HicA toxins contain a double-stranded RNA-binding fold and cleaves both mRNA and tmRNA in vivo, while HicB antitoxins contain a partial RNase H fold and either a helix-turn-helix (HTH) or ribbon-helix-helix domain. It is not known how an HTH DNA-binding domain affects higher-order structure for the HicAB modules. Here, we present crystal structures of the isolated E. coli HicB antitoxin and full-length HicAB complex showing that HicB forms a stable DNA-binding module and interacts in a canonical way with HicA despite the presence of an HTH-type DNA-binding domain. No major structural rearrangements take place upon binding of the toxin. Both structures expose well-ordered DNA-binding motifs allowing a model for DNA binding by the antitoxin to be generated.
Organizational Affiliation:
Department of Molecular Biology and Genetics, Aarhus University, Centre for Bacterial Stress Response and Persistence, Aarhus 8000, Denmark. Electronic address: deb@mbg.au.dk.,Department of Biology, University of Copenhagen, Centre for Bacterial Stress Response and Persistence, Copenhagen 2200, Denmark.,Cellular and Molecular Microbiology, Université Libre de Bruxelles, Gosselies 6041, Belgium.,Department of Molecular Biology and Genetics, Aarhus University, Centre for Bacterial Stress Response and Persistence, Aarhus 8000, Denmark.,Cellular and Molecular Microbiology, Université Libre de Bruxelles, Gosselies 6041, Belgium; Walloon Excellence in Life Sciences and Biotechnology (WELBIO), Brussels, Belgium.
Download Mendeley
Download Endnote
