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SUMMARY:Steve Levene (UTD - USA)
DTSTART:20250214T160000Z
DTEND:20250214T170000Z
DTSTAMP:20260423T041612Z
UID:GEOTOP-A/95
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/GEOTOP-A/95/
 ">Unmasking a hidden DNA-supercoil relaxation activity in a site-specific 
 recombination system</a>\nby Steve Levene (UTD - USA) as part of GEOTOP-A 
 seminar\n\n\nAbstract\nThe tyrosine superfamily of recombinases generates 
 knotted products when acting on inverted target sites in circular\, superc
 oiled DNA. For the Cre/loxP system prime torus knots are formed exclusivel
 y even for strongly supercoiled DNA substrates. This is surprising because
  models that are used to describe the recombination reaction predict the a
 ppearance of complex knot types over the course of repeated reaction cycle
 s due to the release of mechanical energy stored in supercoiled DNA. We so
 lved this puzzle by revealing a hidden DNA-supercoil relaxation activity t
 hat accompanies Cre/loxP recombination through a detailed kinetic analysis
  of the joint distribution of DNA knot type and linking number. A biophysi
 cal model for the time evolution of topological states in circular DNA gen
 erated by multiple reaction cycles of recombination shows that the time-de
 pendent knot distributions observed in experiments can only be quantitativ
 ely explained by a model that includes DNA unwinding. Thus\, the detailed 
 dynamics of transitions between topological states in knotted supercoiled 
 DNA unravels an important aspect of the Cre/loxP recombination mechanism t
 hat could not be discerned without probing the time dependence of the reco
 mbination mechanism.\n
LOCATION:https://researchseminars.org/talk/GEOTOP-A/95/
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