title: An enzyme-catalyzed multistep DNA refolding mechanism in hairpin telomere formation.
abstract: Hairpin telomeres of bacterial linear chromosomes are generated by a DNA cutting-rejoining enzyme protelomerase. Protelomerase resolves a concatenated dimer of chromosomes as the last step of chromosome replication, converting a palindromic DNA sequence at the junctions between chromosomes into covalently closed hairpins. The mechanism by which protelomerase transforms a duplex DNA substrate into the hairpin telomeres remains largely unknown. We report here a series of crystal structures of the protelomerase TelA bound to DNA that represent distinct stages along the reaction pathway. The structures suggest that TelA converts a linear duplex substrate into hairpin turns via a transient strand-refolding intermediate that involves DNA-base flipping and wobble base-pairs. The extremely compact di-nucleotide hairpin structure of the product is fully stabilized by TelA prior to strand ligation, which drives the reaction to completion. The enzyme-catalyzed, multistep strand refolding is a novel mechanism in DNA rearrangement reactions.
authors: Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors: Ke
authors: K
authors: Shi
authors: Wai Mun
authors: WM
authors: Huang
authors: Hideki
authors: H
authors: Aihara
mesh_terms: D016960:Agrobacterium tumefaciens / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry; D002876:Chromosomes, Bacterial / Q000378:metabolism; D018360:Crystallography, X-Ray; D004261:DNA Replication; D042522:DNA Replication Timing; D004269:DNA, Bacterial / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry; D015321:Gene Rearrangement; D009690:Nucleic Acid Conformation; D016615:Telomere / Q000378:metabolism* / Q000648:ultrastructure*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins
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