Ms. Elizabeth Villa
University of Illinois
Urbana, IL

Thursday, March 17, 2005
2:00 pm (CT)
1227 Beckman Institute

Abstract

The lac repressor (lacR) is a prototype regulatory protein. It binds to two operator sites of the E. coli genome and forces the intermediate DNA into a loop, thus preventing transcription of three genes that code for enzymes involved in lactose digestion. The structure of the protein is known without the DNA loop and has now been established through advanced computer simulation with the intact DNA loop included. The simulation reaveals also the dynamics of teh lacR - DNA system. LacR is found to absorb the strain from the looped DNA through rotation of its two head groups, giving the protein great flexibility to adapt to any forces arising from its interaction with DNA. This flexibility permits lacR to wrestle DNA and keep it in a loop form.