= Branch migration
<Branch migration> is movement of the strand-exchange point in a <Holliday junction>. Successive changes in <base pairing> shift the junction along homologous <DNA> without requiring a new break in each phosphodiester backbone. Moving the boundary changes the extent of <heteroduplex DNA>, where strands from different parental <DNA> <molecules> pair together.
An illuminating experiment built two double-stranded <DNA> substrates with complementary single-stranded tails. Pairing the tails formed a four-stranded junction at one end. Complete <branch migration> to the opposite end produced two strand-exchanged duplex products, giving an observable endpoint for a process otherwise occurring along a molecular junction.<The kinetics of spontaneous DNA branch migration by I. G. Panyutin and P. Hsieh>[Abstract; substrate design, annealing and complete strand exchange]{ref}
The spontaneous reaction depended strongly on the surrounding <ions>: under the reported conditions, removing <magnesium> made it roughly a thousand times faster. This is not a universal speed for <DNA> exchange inside a <cell>; the experiment isolated a spontaneous process whose kinetics depend on junction structure and solution conditions.<The kinetics of spontaneous DNA branch migration by I. G. Panyutin and P. Hsieh>[Abstract; magnesium-dependent rate comparison and structural interpretation]{ref}
Back to article page
