Featured Speakers Fall 2017

All seminars are held in room 240 Physical Sciences
Tuesdays, 12:00 PM - 1:00 PM
unless otherwise indicated

ChienOct 3
Dr. Peter Chien
Associate Professor, Department of Biochemistry and Molecular Biology
University of Massachusetts Amherst 
Seminar Title TBD

Regulated proteolysis in bacterial stress responses and cell cycle progression

Protein degradation is an essential process for all biological life. Damaged or improperly folded proteins need to be cleared from the cell before they elicit toxic effects. Regulatory proteins need to be degraded so that the response they support exists only as long as it is necessary. However, as proteolysis is an irreversible event, great care must be taken to only degrade those factors as needed without disturbing the balance of other proteins.  In bacteria, energy dependent AAA+ proteases are responsible for destroying proteins that fail quality control and for regulated degradation of proteins needed for normal growth or during stress responses.  For example, we have shown how the Clp family of proteases in Caulobacter crescentus is responsible for controlling cell cycle progression and how the Lon protease elicits a cell cycle arrest upon proteotoxic stress.  In this seminar, I will describe our recent studies describing how regulated proteolysis coordinates growth with division and the role of regulated degradation in the DNA damage response.

ChouOct 24
Dr. Seemay Chou
Assistant Professor, Department of Biochemistry & Biophysics
University of California, San Francisco

From bacteria to ticks: lessons in antimicrobial defense

The bacterial cell wall provides key structural support and shape for bacterial cells and is therefore an important antimicrobial target across a broad range of organisms. For example, Gram-negative bacteria employ lytic, cell wall-degrading enzymes to directly target neighboring competitor cells via the type VI secretion system (T6SS). Bacterial competition through the exchange of these T6S amidase effector (Tae) toxins can significantly influence the composition of polymicrobial communities. The functional importance of the Tae enzymes is further exemplified by our recent identification of tae gene acquisition by diverse eukaryotes through several independent instances of cross-kingdom horizontal gene transfer. Using a combination of biochemical and genetic approaches, we aim to understand how Tae and Dae specificity for different cell wall peptidoglycan structures shapes the outcome of both interbacterial and host-microbe interactions. We are also investigating the antibacterial mechanism of a Dae representative in the tick disease vector Ixodes scapularis in order to understand its role in controlling the colonization and transmission of tick-borne pathogens.



Atilla-GokcumenDec 5
Dr. Gunes Ekin Atilla-Gokcumen
Assistant Professor, Department of Chemistry
State University of New York, Buffalo

Non-canonical Roles of Lipids in Different Cellular Processes

Lipids are a highly regulated and chemically diverse class of biomolecules. The biosynthesis and transport of these molecules are controlled by a considerable number of proteins, which facilitate spatio-temporal regulation of lipids during different fundamental cellular processes such as cell division and death. Although lipids are traditionally recognized as molecules for energy storage and as structural components of membranes, there is a growing appreciation of their chemical diversity. Lipids are being increasingly recognized for their signaling roles, capable of transmitting information within and between cells. I will discuss recent discoveries from our laboratory and others on the involvement of polyunsaturated triacylglycerols, very long chain fatty acids and ceramides in different cellular fates. I will also highlight recent work on the development of innovative methods that have enabled the recognition of previously unknown roles for lipids in different biological processes. Gaining a better fundamental understanding of the physiological roles of lipids will ultimately enable new diagnostic and therapeutic strategies for different diseases.

Dr. Ekin Atilla-Gokcumen  
Broadly, I am interested in studying how metabolites contribute to different cellular processes, primarily by using LC-MS based profiling. The current focus in my laboratory is towards investigating a subgroup of metabolites, lipids. Lipids are a broad class of biomolecules whose primary role is thought to be forming permeability barriers, which define cellular borders and compartments within them. Increasingly, however, they are recognized to play critical roles as signaling molecules both within cells and between cells, as lipids themselves, or following transformation by hydrolysis, oxidation or other modifications. Particularly, we aim to address the functional significance of lipids in different decision making processes of cells such as programed cell deaths and senescence. By using LC-MS based global lipid profiling, we construct comprehensive maps of the changes of the lipid composition during these events. Identification of species that change significantly provides the groundwork for studying the function of these molecules. Along these lines, we build lipid-derived tool compounds to study the localization and interaction partners of these molecules. We believe that identification of species that change significantly can be exploited towards using these lipids as biomarkers and present therapeutic applications. As a chemical biologist with experience in lipidomics and cell biology, my goals and approaches lie at the intersection of chemistry and biology, which puts me in a unique position to identify lipids in different cellular processes and to study their function.