(Speaker Term: July 1, 2014 - June 30, 2016)
William Margolin (term: 7/1/14 through 6/30/16)
Department of Microbiology and Molecular Genetics
University of Texas Medical School at Houston
6431 Fannin Street
Houston, TX 77030
Speaker’s Website: http://mmg.uth.tmc.edu/faculty/faculty-william-margolin.html
ASM MEMBERSHIP AFFILIATION – William Margolin
Primary Division: J (Cell and Structural Biology)
Secondary Division: H (Genetics & Molecular Biology)
LECTURE TOPICS AND DESCRIPTIONS – William Margolin
Splitsville: How Bacterial Cells Mark their Midpoint and Use it for Binary Fission
To divide by binary fission, rod-shaped bacteria such as E. coli or B. subtilis select their cell midpoint by deploying a morphogen gradient. This gradient consists of proteins that localize to cell poles or nucleoids and which negatively regulate the assembly of FtsZ, the primary structural component of the cell division machinery. The result is that FtsZ assembles into filaments at the cell midpoint, where the level of negative regulation by the morphogen gradient is lowest.
Feeling the Pinch: Regulation and Function of the Bacterial Cell Division Protein Machine
Once FtsZ assembles into a ring, it recruits numerous additional protein factors that traverse the cytoplasmic membrane and trigger synthesis of the division septum. We currently are studying how these proteins interact with each other in space and time, how septum synthesis is triggered and coordinated with membrane ingression and chromosome segregation, and how the machine is ultimately disassembled. We are also studying the mode of action of various small protein regulators of the machine, including those produced by bacteriophages.
Cryo-electron Tomography of E. coli Minicells to Visualize Large Protein Machines at the Cell Surface
Fluorescence microscopy and electron microscopy are powerful imaging methods that can visualize macromolecular structures in living cells at low resolution (~200 nm) or fixed, stained cells at high resolution. Cryo-electron tomography (cryo-ET) can bridge this gap, allowing visualization of protein structures in intact, unfixed cells at resolutions approaching 3 nm. E. coli cells are generally too thick to obtain sufficient contrast by cryo-ET, but tiny minicells made from E. coli circumvent this problem. In collaboration with several laboratories, we have used cryo-ET of minicells to shed new light on conformational changes during bacteriophage infection as well as the structure of chemoreceptor arrays.
BIOGRAPHICAL SKETCH – William Margolin
Dr. Margolin has been interested in bacterial cell biology for over 20 years. He pioneered the visualization of bacterial cytoskeletal proteins and their dynamics in living bacterial cells, and continues to study how these proteins function in cytokinesis and cellular organization. He recently has embarked on a collaborative project that uses engineered bacterial minicells to visualize bacteriophage infection and chemoreceptor arrays by cryo-electron tomography. Dr. Margolin has convened numerous symposia at ASM meetings and was the ASM Division J Lecturer in 2012. He has served as Councilor and Chair for Division I of ASM and has been on the editorial board or an Editor for Journal of Bacteriology since 2000. Dr. Margolin has been a Professor at the University of Texas-Houston since 2005 and Director of the Microbiology and Molecular Genetics Graduate Program there since 2009. He is well known for his many clearly written reviews and commentaries on bacterial cell biology topics, and has given 85 invited local, national and international oral presentations during his faculty career.
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