Abstract: Cells are protected by a complex molecular barrier involved in important biological functions. This interface is often targeted or traversed by biologically-active molecules that can perturb the cell architecture with significant consequences on cell functions and survival. It is thus of great importance to provide tools to study interactions with cell constituents. “In-cell” NMR is an emerging field that wishes to provide molecular-level information on the structure and dynamics of intact cells. It is however challenging considering that each nucleus of each cell constituent will produce a signal on the spectrum. The objective of our work is thus to develop methodologies to achieve selectivity in complexity. We have a special interest for microorganisms because they are at the heart of important socioeconomic problems such as bacterial resistance, or contaminant threats to microalgae. In this seminar, we will show how the specific deuteration of membrane lipid chains combined to 2H in vivo NMR allowed refining the action mechanism of antimicrobial peptides on Escherichia coli and Bacillus subtilis. We will then present the case of non-specific labelling where NMR strategies were used to selectively focus on unique constituents of fully 13C labelled intact Chlamydomonas reinhardtii microalgae, such as the cell wall, starch, and lipids.
Bio: Isabelle Marcotte received her Ph.D. from Université Laval in 2003, under the supervision of Prof. Michele Auger, where she studied membrane-peptide interactions by NMR and FTIR spectroscopy. She then moved to Switzerland to perform postdoctoral research on solid-state NMR study of spider silk with Prof. Beat H. Meier at ETH-Zürich. In 2006, she established her own lab in the Department of Chemistry of the Université du Québec à Montréal (UQAM) where her research focuses on molecular interactions with cells and membranes, as well as the structure of natural protein fibers, such as mussel byssus, by solid-state NMR. In 2014, she received the Young Researcher Award of UQAM's Faculty of Sciences for remarkable debut in research and promising impact. She became full professor in 2015, and is now Vice-dean of research of the Faculty of Sciences since June 2017.