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Elife. 2018 Oct 5;7. pii: e39611. doi: 10.7554/eLife.39611.

Multiple serine transposase dimers assemble the transposon-end synaptic complex during IS607-family transposition.

Author information

1
Department of Biological Chemistry, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, United States.
2
Department of Energy Institute of Genomics and Proteomics, University of California at Los Angeles, Los Angeles, United States.
3
Molecular Biology Institute, University of California at Los Angeles, Los Angeles, United States.

Abstract

IS607-family transposons are unusual because they do not have terminal inverted repeats or generate target site duplications. They encode two protein-coding genes, but only tnpA is required for transposition. Our X-ray structures confirm that TnpA is a member of the serine recombinase (SR) family, but the chemically-inactive quaternary structure of the dimer, along with the N-terminal location of the DNA binding domain, are different from other SRs. TnpA dimers from IS1535 cooperatively associate with multiple subterminal repeats, which together with additional nonspecific binding, form a nucleoprotein filament on one transposon end that efficiently captures a second unbound end to generate the paired-end complex (PEC). Formation of the PEC does not require a change in the dimeric structure of the catalytic domain, but remodeling of the C-terminal α-helical region is involved. We posit that the PEC recruits a chemically-active conformer of TnpA to the transposon end to initiate DNA chemistry.

KEYWORDS:

DNA transposition; E. coli; Helicobacter pylori; Mycobacteria tuberculosis; Sulfolobus islandicus; biochemistry; chemical biology; chromosomes; gene expression; nucleoprotein complex; serine recombinase

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