title: RecA-binding pilE G4 sequence essential for pilin antigenic variation forms monomeric and 5' end-stacked dimeric parallel G-quadruplexes.
abstract: Neisseria gonorrhoeae is an obligate human pathogen that can escape immune surveillance through antigenic variation of surface structures such as pili. A G-quadruplex-forming (G4) sequence (5'-G(3)TG(3)TTG(3)TG(3)) located upstream of the N. gonorrhoeae pilin expression locus (pilE) is necessary for initiation of pilin antigenic variation, a recombination-based, high-frequency, diversity-generation system. We have determined NMR-based structures of the all parallel-stranded monomeric and 5' end-stacked dimeric pilE G-quadruplexes in monovalent cation-containing solutions. We demonstrate that the three-layered all parallel-stranded monomeric pilE G-quadruplex containing single-residue double-chain reversal loops, which can be modeled without steric clashes into the 3 nt DNA-binding site of RecA, binds and promotes E. coli RecA-mediated strand exchange in vitro. We discuss how interactions between RecA and monomeric pilE G-quadruplex could facilitate the specialized recombination reactions leading to pilin diversification.
authors.affiliation: Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, 10065, USA. v.kuryavyi@gmail.com
authors.forename: Vitaly
authors.initials: V
authors.lastname: Kuryavyi
authors.forename: Laty A
authors.initials: LA
authors.lastname: Cahoon
authors.forename: H Steven
authors.initials: HS
authors.lastname: Seifert
authors.forename: Dinshaw J
authors.initials: DJ
authors.lastname: Patel
mesh_terms: D000942:Antigens, Bacterial / Q000737:chemistry / Q000235:genetics*; D020029:Base Pairing; D001483:Base Sequence; D001665:Binding Sites; D004269:DNA, Bacterial / Q000737:chemistry*; D041961:Deuterium Exchange Measurement; D029968:Escherichia coli Proteins / Q000737:chemistry*; D036781:Fimbriae Proteins / Q000737:chemistry / Q000235:genetics*; D054856:G-Quadruplexes; D020862:GC Rich Sequence; D057131:Immune Evasion; D008958:Models, Molecular; D009344:Neisseria gonorrhoeae / Q000235:genetics*; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D011938:Rec A Recombinases / Q000737:chemistry*
chemical_list: D000942:Antigens, Bacterial; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D036781:Fimbriae Proteins; D011938:Rec A Recombinases