title: Crystallization and preliminary X-ray analysis of two variants of the Escherichia coli O157 ParE2-PaaA2 toxin-antitoxin complex.
abstract: The paaR2-paaA2-parE2 operon is a three-component toxin-antitoxin module encoded in the genome of the human pathogen Escherichia coli O157. The toxin (ParE2) and antitoxin (PaaA2) interact to form a nontoxic toxin-antitoxin complex. In this paper, the crystallization and preliminary characterization of two variants of the ParE2-PaaA2 toxin-antitoxin complex are described. Selenomethionine-derivative crystals of the full-length ParE2-PaaA2 toxin-antitoxin complex diffracted to 2.8 Å resolution and belonged to space group P41212 (or P43212), with unit-cell parameters a = b = 90.5, c = 412.3 Å. It was previously reported that the full-length ParE2-PaaA2 toxin-antitoxin complex forms a higher-order oligomer. In contrast, ParE2 and PaaA213-63, a truncated form of PaaA2 in which the first 12 N-terminal residues of the antitoxin have been deleted, form a heterodimer as shown by analytical gel filtration, dynamic light scattering and small-angle X-ray scattering. Crystals of the PaaA213-63-ParE2 complex diffracted to 2.7 Å resolution and belonged to space group P6122 (or P6522), with unit-cell parameters a = b = 91.6, c = 185.6 Å.
authors.affiliation: Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium.
authors.forename: Yann G J
authors.initials: YG
authors.lastname: Sterckx
authors.affiliation: Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium.
authors.forename: Sarah
authors.initials: S
authors.lastname: Haesaerts
authors.affiliation: Génétique et Physiologie Bactérienne, IBMM, Université Libre de Bruxelles (ULB), 12 Rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium.
authors.forename: Laurence
authors.initials: L
authors.lastname: Van Melderen
authors.affiliation: Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium.
authors.forename: Remy
authors.initials: R
authors.lastname: Loris
mesh_terms: D000595:Amino Acid Sequence; D000992:Antitoxins / Q000737:chemistry*; D001427:Bacterial Toxins / Q000737:chemistry* / Q000235:genetics; D001483:Base Sequence; D003001:Cloning, Molecular; D003460:Crystallization; D018360:Crystallography, X-Ray / Q000379:methods*; D004247:DNA; D019453:Escherichia coli O157 / Q000737:chemistry*; D008969:Molecular Sequence Data; D016366:Open Reading Frames
chemical_list: D000992:Antitoxins; D001427:Bacterial Toxins; D004247:DNA
keywords: Escherichia coli O157; ParE2–PaaA2; toxin–antitoxin