EMD-13440
Cryo-EM helical reconstruction of E. coli TnsB in complex with right end fragment of Tn7 transposon
EMD-13440
Helical reconstruction3.79 Å
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Map released: 15/06/2022
Last modified: 03/08/2022
Sample Organism:
Escherichia coli
Sample: TnsB-DNA complex
Deposition Authors: Czarnocki-Cieciura M
,
Kaczmarska Z
Sample: TnsB-DNA complex
Deposition Authors: Czarnocki-Cieciura M
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Structural basis of transposon end recognition explains central features of Tn7 transposition systems.
Kaczmarska Z,
Czarnocki-Cieciura M
,
Gorecka-Minakowska KM,
Wingo RJ,
Jackiewicz J,
Zajko W,
Poznanski JT
,
Rawski M
,
Grant T,
Peters JE
,
Nowotny M
(2022) Mol Cell , 82 , 2618 - 2632.e7
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(2022) Mol Cell , 82 , 2618 - 2632.e7
Abstract:
Tn7 is a bacterial transposon with relatives containing element-encoded CRISPR-Cas systems mediating RNA-guided transposon insertion. Here, we present the 2.7 Å cryoelectron microscopy structure of prototypic Tn7 transposase TnsB interacting with the transposon end DNA. When TnsB interacts across repeating binding sites, it adopts a beads-on-a-string architecture, where the DNA-binding and catalytic domains are arranged in a tiled and intertwined fashion. The DNA-binding domains form few base-specific contacts leading to a binding preference that requires multiple weakly conserved sites at the appropriate spacing to achieve DNA sequence specificity. TnsB binding imparts differences in the global structure of the protein-bound DNA ends dictated by the spacing or overlap of binding sites explaining functional differences in the left and right ends of the element. We propose a model of the strand-transfer complex in which the terminal TnsB molecule is rearranged so that its catalytic domain is in a position conducive to transposition.
Tn7 is a bacterial transposon with relatives containing element-encoded CRISPR-Cas systems mediating RNA-guided transposon insertion. Here, we present the 2.7 Å cryoelectron microscopy structure of prototypic Tn7 transposase TnsB interacting with the transposon end DNA. When TnsB interacts across repeating binding sites, it adopts a beads-on-a-string architecture, where the DNA-binding and catalytic domains are arranged in a tiled and intertwined fashion. The DNA-binding domains form few base-specific contacts leading to a binding preference that requires multiple weakly conserved sites at the appropriate spacing to achieve DNA sequence specificity. TnsB binding imparts differences in the global structure of the protein-bound DNA ends dictated by the spacing or overlap of binding sites explaining functional differences in the left and right ends of the element. We propose a model of the strand-transfer complex in which the terminal TnsB molecule is rearranged so that its catalytic domain is in a position conducive to transposition.