BEGIN:VCALENDAR VERSION:2.0 METHOD:PUBLISH PRODID:-//Missouri State University/Calendar of Events//EN CALSCALE:GREGORIAN X-WR-TIMEZONE:America/Chicago BEGIN:VTIMEZONE TZID:America/Chicago BEGIN:DAYLIGHT TZOFFSETFROM:-0600 TZOFFSETTO:-0500 DTSTART:20070311T020000 RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU TZNAME:CDT END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:-0500 TZOFFSETTO:-0600 DTSTART:20071104T020000 RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU TZNAME:CST END:STANDARD END:VTIMEZONE BEGIN:VEVENT UID:c17b09eb-aaf3-4849-b90d-c9da9c3fd578.218141@calendar.missouristate.edu CREATED:20211004T162915Z LAST-MODIFIED:20211004T162915Z LOCATION:Kemper Hall 206 SUMMARY:PAMS Seminar: "Force-based detection of sub-millisecond topoisomer ase IA dynamics" by Dr. Maria Mills DESCRIPTION:Dr. Maria MillsDepartment of Physics & AstronomyUniversity of Missouri\n\n\nAbstract:Single molecule fluorescence and manipulation tech niques have enabled measurements of nanometer-scale changes in molecular conformations. These techniques have been particularly useful for the stu dy of biological molecules. However\, the timescales of many biomolecular motions remain a challenge for single molecule measurements. Many protei n and nucleic acid conformational changes happen on the ns-µs timescale\, while single molecule measurements that rely on camera-based detection a re limited to ms-s timescales. We have developed a novel magnetic tweezer s assay that uses an applied force to probe the fast conformational dynam ics of type IA topoisomerases. Type IA topoisomerases bind and cleave sin gle-stranded DNA and pass a second strand through the transient break. Wh ile it has long been assumed that these proteins must undergo a conformat ional change in order to pass this second strand\, this gate opening had never been observed. By applying a force against closing\, we were able t o increase the lifetime of the enzyme’s open state and observe the openin g and closing of a protein-mediated DNA gate. We found that following cle avage of single-stranded DNA\, the gate opens by as much as 6.6 nm and ca n close against forces in excess of 16 pN. From the force-rate dependence \, we calculated an average lifetime of the open state at equilibrium of ~500 µs. These experiments allowed us to delineate the full kinetic pathw ay of type IA topoisomerase-ssDNA kinetics.\n\n\nThis seminar will be in Kemper 206. X-ALT-DESC;FMTTYPE=text/html:<html><head><title></title></head><body><p><s trong>Dr.&nbsp\;Maria Mills<br>Department of Physics &amp\; Astronomy<br> University of Missouri</strong></p>\n<p>Abstract:<br>Single molecule fluo rescence and manipulation techniques have enabled measurements of nanomet er-scale changes in molecular conformations. These techniques have been p articularly useful for the study of biological molecules. However\, the t imescales of many biomolecular motions remain a challenge for single mole cule measurements. Many protein and nucleic acid conformational changes h appen on the ns-µs timescale\, while single molecule measurements that re ly on camera-based detection are limited to ms-s timescales. We have deve loped a novel magnetic tweezers assay that uses an applied force to probe the fast conformational dynamics of type IA topoisomerases. Type IA topo isomerases bind and cleave single-stranded DNA and pass a second strand t hrough the transient break. While it has long been assumed that these pro teins must undergo a conformational change in order to pass this second s trand\, this gate opening had never been observed. By applying a force ag ainst closing\, we were able to increase the lifetime of the enzyme’s ope n state and observe the opening and closing of a protein-mediated DNA gat e. We found that following cleavage of single-stranded DNA\, the gate ope ns by as much as 6.6 nm and can close against forces in excess of 16 pN. From the force-rate dependence\, we calculated an average lifetime of the open state at equilibrium of ~500 µs. These experiments allowed us to de lineate the full kinetic pathway of type IA topoisomerase-ssDNA kinetics. </p>\n<p>This seminar will be in Kemper 206.</p></body></html> DTSTART;TZID=America/Chicago:20211021T160000 DTEND;TZID=America/Chicago:20211021T170000 SEQUENCE:0 URL:https://physics.missouristate.edu/seminars.htm CATEGORIES:Public,Alumni,Current Students,Faculty,Future Students,Staff END:VEVENT END:VCALENDAR