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Biophysics Seminar: Elizabeth Gichana and Marcos Núñez, Biophysics Ph.D. Candidates

Elizabeth Gichana Title:"Investigating the influence of sequence of the folding mechanism of RNaseH using a structure based model" and Marcos Nunez Title: "Visualizing phase-like domains in B cell plasma membranes using super-resolution microscopy"
Friday, October 21, 2016
4:00-5:00 PM
1300 Chemistry Dow Lab Map
Elizabeth Gichana:

Title: "Investigating the influence of sequence of the folding mechanism of RNaseH using a structure based model"

Abstract:
There are two major sources of frustration in a protein folding – energetic and topological. Energy landscape theory posits that main-chain topology is the major determinant in the folding mechanism of a protein. What is less well understood is the role that sequence effects play. To gain insight into this challenging problem, we utilize ancestral sequences reconstructed along mesophilic and thermophilic lineages of ribonuclease H (RNaseH) leading back to a common ancestor. This family of proteins share function and topology and have high sequence homology but differ in their biophysical properties. We investigate the role that variation in sequence over these evolutionary timescales alters the energy landscape of RNaseH to give rise to these differences by employing coarse-grained molecular dynamics simulations using a structure-based Go-like model to investigate folding mechanisms.

and

Marcos Núñez :

Title: Visualizing phase-like domains in B cell plasma membranes using super-resolution microscopy

Abstract: Protein sorting based on liquid-ordered (Lo) or liquid-disordered (Ld) phase preference is readily observed in giant plasma membrane vesicles (GPMVs) at low temperatures but is not as easily detected in the intact cells from which they are derived. Here we utilize two-color super-resolution microscopy in combination with cross-correlation analysis to quantify the sorting of two minimal inner leaflet anchored-peptides proximal to clusters of cholera toxin B subunit (CTxB) in chemically fixed CH27 B cells. We find that the local density of a Lo-partitioning peptide is increased while the local density of an Ld-partitioning peptide is reduced in the vicinity of CTxB clusters when compared to the average density of peptides on the cell surface. This alongside other experimental results supports the hypothesis that intact cell plasma membranes can contain lipid domains which resemble Lo and Ld phases. In this talk, I will discuss my efforts to make this measurement more quantitative by surveying different fluorescent probes and CTxB clustering conditions so that I can compare the magnitude of partitioning in response to different physical perturbations.
Building: Chemistry Dow Lab
Event Type: Workshop / Seminar
Tags: Chemistry
Source: Happening @ Michigan from LSA Biophysics