EMD-13440

Helical reconstruction
3.79 Å
EMD-13440 Deposition: 20/08/2021
Map released: 15/06/2022
Last modified: 03/08/2022
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-13440

Cryo-EM helical reconstruction of E. coli TnsB in complex with right end fragment of Tn7 transposon

EMD-13440

Helical reconstruction
3.79 Å
EMD-13440 Deposition: 20/08/2021
Map released: 15/06/2022
Last modified: 03/08/2022
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Escherichia coli
Sample: TnsB-DNA complex

Deposition Authors: Czarnocki-Cieciura M , Kaczmarska Z
Structural basis of transposon end recognition explains central features of Tn7 transposition systems.
PUBMED: 35654042
DOI: doi:10.1016/j.molcel.2022.05.005
ISSN: 1097-2765
ASTM: MOCEFL
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.