Abstract
The termini of linear chromosomes are protected by specialized DNA structures known as telomeres that also facilitate the complete replication of DNA ends. The simplest type of telomere is a covalently closed DNA hairpin structure found in linear chromosomes of prokaryotes and viruses. Bidirectional replication of a chromosome with hairpin telomeres produces a catenated circular dimer that is subsequently resolved into unit-length chromosomes by a dedicated DNA cleavage-rejoining enzyme known as a hairpin telomere resolvase (protelomerase). Here we report a crystal structure of the protelomerase TelK from Klebsiella oxytoca phage φ{symbol}KO2, in complex with the palindromic target DNA. The structure shows the TelK dimer destabilizes base pairing interactions to promote the refolding of cleaved DNA ends into two hairpin ends. We propose that the hairpinning reaction is made effectively irreversible by a unique protein-induced distortion of the DNA substrate that prevents religation of the cleaved DNA substrate.
Original language | English (US) |
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Pages (from-to) | 901-913 |
Number of pages | 13 |
Journal | Molecular Cell |
Volume | 27 |
Issue number | 6 |
DOIs | |
State | Published - Sep 21 2007 |
Bibliographical note
Funding Information:This work was supported by a grant from the National Institutes of Health (GM59902 to T.E.) and a grant from the National Science Foundation (MCB-021324 to W.M.H.).
Keywords
- DNA
- MICROBIO