Friends of the late Tracy M. Sonneborn established a lectureship in his memory in 1981. Support for this lecture has been provided by the Sonneborn Lecture Fund and the Department of Biology.
Tracy M. Sonneborn Lecture Series
Professor of Biophysics and Biophysical Chemistry
Johns Hopkins School of Medicine
Spatial organization of biological functions—a single-molecule review of bacterial cell division
Wednesday, November 8, 2023
Myers Hall 130
My laboratory focuses on developing novel single-molecule imaging tools in live cells to probe various aspects of microbial cellular processes. We are broadly interested in understanding how the molecular constituents of bacterial cellular processes are spatially organized and what essential functions such an organization conveys. In this talk, I will discuss our recent work on the structure, function, and dynamics of the bacterial cell division machinery. Using single-molecule imaging in live E. coli cells, we first illustrated the structural organization of the bacterial cytokinesis ring formed by the tubulin homolog FtsZ protein. We next found that FtsZ uses its GTP hydrolysis to power treadmilling dynamics and function as a linear motor to transport sPG synthase enzymes evenly along the septum to ensure smooth, symmetric septum formation. We discovered that the activity of these enzymes is spatially regulated through their differential coupling to two distinct tracks along the septum. Through structural investigations, we provided molecular details of how the core division complex activates the essential sPG synthase complex. Our work point opens new directions to study the precise spatial coordination and regulation of the large ensemble of cell division proteins.
About Tracy Sonneborn
Aside from a few years at Johns Hopkins University where he received the Ph.D. degree, Tracy Sonneborn spent his entire career at Indiana University. His devotion to the study of Paramecium established him as the world leader in biology and genetics of the Protozoa; indeed it is no exaggeration to say that he founded the modern era of study in these areas.
One of his major contributions was in demonstrating that preexisting structures in cells can repeatedly determine the patterns of new structures through many generations. Although recognized as an important exception to Mendelian inheritance and a critical element in prion diseases, the mechanism of structural inheritance in biology is not yet understood.
With precision, thoroughness, and infectious enthusiasm, Tracy Sonneborn also contributed unstintingly to teaching at Indiana University. In spite of the many attempts to entice him away, he remained loyal to IU, finding here the environment he thought was best. To honor his contributions to science and his outstanding career Tracy Sonneborn’s friends and colleagues initiated the Sonneborn Lectureship in 1981.
"Whatever the final outcome of studies of these phenomena, he must take his place among the most brilliant and devoted experimentalists in the history of biology and a true giant, like no other, in the field of protozoan research." John Preer