Finzi Lab Research
Graduate student Yue Ding and Professor Laura Finzi, together with collaborators, probed the effect of DNA supercoiling on the stability of the lambda bacteriophage genetic switch between lysogeny (quiescence) and lysis (virulence). DNA supercoiling is an indicator of cell health and a fundamental parameter involved in the compaction of DNA as well as in the regulation of DNA physiology. This study showed that the lambda repressor efficiently partitioned plasmids into topological domains and formed barriers to the passage of supercoiling from one into another. Furthermore, in single DNA molecules twisted with magnetic tweezers, lambda repressor-mediated DNA loops confined as much as -15 to +11% supercoiling. Finally under gentle tensions likely to occur in vivo, supercoiling was essential for looping. The lambda repressor may exploit supercoil-driven looping events to regulate the lysogenic/lytic switch.
This research was published in PNAS, 111, 15402-15407, Oct. 2014. weblink http://www.pnas.org/content/111/43/15402.short