January 12, 2022, Online 6:30 pm PDT
OSSC Online Meeting
“Fluorescence Spectroscopy of Exciton-Coupled Cyanine Dimers”
Dr. Andrew H. Marcus, Center for Optical Molecular & Quantum Science, Univ. Oregon
Agenda and Registration
Wednesday, January 12th, 2021
Prior Registration Required
Login Credentials emailed on Jan 12.
Attendee Logon 6:30pm
7:00pm –7:15pm OSSC President Opens Meeting & Speaker Introduction
7:15pm—8:15 Professor Marcus Presentation
8:15pm--8:45pm Q & A
9:00pm Meeting Closes
On-Line Registration Closes Jan 11, 2022
Abstract: In DNA replication, genome regulatory proteins must recognize, bind to, and carry out their functions near single-stranded (ss) – double-stranded (ds) DNA junctions. The local conformations of the sugar-phosphate backbones of DNA near ss–ds junctions undergo ‘breathing’ fluctuations to permit the proper binding of proteins that function at these sites. In this talk, I will discuss optical interferometry-based experiments developed in my lab – both at the ensemble and single-molecule levels – to study DNA breathing of fluorescent probe-labeled model DNA fork constructs, which contain a pair of cyanine chromophores [i.e., a (Cy3)2 dimer] incorporated into the sugar-phosphate backbones at various positions relative to the ss – ds DNA fork junction. These experiments apply a continuous phase sweep to the relative optical path of an interferometer and the source laser is used to resonantly excite the sample. The ensuing modulated fluorescence is detected as a function of the phase of the exciting optical field, and information is obtained about the local structure and fluctuations of the (Cy3)2 dimer-labeled sites.
Experiments using a continuously rotating polarized laser differentially excite the polarized excitons of the (Cy3)2 dimer in a single-molecule sample, and the weak modulated fluorescence is detected using a phase-tagged photon counting (PTPC) method. These experiments directly monitor the breathing fluctuations at the (Cy3)2 dimer-labeled DNA fork junction and provide insights to understand the mechanisms of protein-DNA binding and macromolecular complex assembly
About our speaker: Andy Marcus is a Professor of Chemistry and Biochemistry at the University of Oregon, where he joined the faculty in 1996. He received his B.A. in 1988 from the University of California at San Diego, his Ph.D. in 1994 from Stanford University, and he did postdoctoral work at the University of Chicago. His research focuses on the development of linear and nonlinear spectroscopic methods under low signal conditions and
the applications of these methods to problems related to protein-DNA interactions.