Structure of a RecT/Redβ family recombinase in complex with a duplex intermediate of DNA annealing.

Autor: Caldwell, Brian J., Norris, Andrew S., Karbowski, Caroline F., Wiegand, Alyssa M., Wysocki, Vicki H., Bell, Charles E.
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Zdroj: Nature Communications; 12/21/2022, Vol. 13 Issue 1, p1-14, 14p
Abstrakt: Some bacteriophage encode a recombinase that catalyzes single-stranded DNA annealing (SSA). These proteins are apparently related to RAD52, the primary human SSA protein. The best studied protein, Redβ from bacteriophage λ, binds weakly to ssDNA, not at all to dsDNA, but tightly to a duplex intermediate of annealing formed when two complementary DNA strands are added to the protein sequentially. We used single particle cryo-electron microscopy (cryo-EM) to determine a 3.4 Å structure of a Redβ homolog from a prophage of Listeria innocua in complex with two complementary 83mer oligonucleotides. The structure reveals a helical protein filament bound to a DNA duplex that is highly extended and unwound. Native mass spectrometry confirms that the complex seen by cryo-EM is the predominant species in solution. The protein shares a common core fold with RAD52 and a similar mode of ssDNA-binding. These data provide insights into the mechanism of protein-catalyzed SSA. Specific ssDNA binding proteins promote the annealing of complementary strands. Here the authors reveal an intermediate of annealing in which a duplex DNA is bound in an unusual conformation that is highly extended and unwound for the ssDNA binding protein Redβ from bacteriophage λ. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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