7PIK

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

Summary for 7PIK

• Entry DOI: 10.2210/pdb7pik/pdb
• EMDB information: 13439
• Descriptor: Transposon Tn7 transposition protein TnsB, Right end fragment of Tn7 transposon (3 entities in total)
• Functional Keywords: complex, nuclease, dna binding protein, tn7, transposon
• Biological source: Escherichia coli; More
• Total number of polymer chains: 7
• Total formula weight: 448283.26

Authors

Kaczmarska, Z.,Czarnocki-Cieciura, M.,Rawski, M.,Nowotny, M. (deposition date: 2021-08-20, release date: 2022-06-15, Last modification date: 2024-07-17)

Primary citation

Kaczmarska, Z.,Czarnocki-Cieciura, M.,Gorecka-Minakowska, K.M.,Wingo, R.J.,Jackiewicz, J.,Zajko, W.,Poznanski, J.T.,Rawski, M.,Grant, T.,Peters, J.E.,Nowotny, M.
Structural basis of transposon end recognition explains central features of Tn7 transposition systems.
Mol.Cell, 82:2618-, 2022

PubMed 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.

PubMed: 35654042
DOI: 10.1016/j.molcel.2022.05.005

Experimental method

ELECTRON MICROSCOPY (2.68 Å)