I. The critical role of spatial organization in bacterial cell function
II. DNA segregation and active intracellular transport in bacteria
Part I: The critical role of spatial organization in bacterial cell function
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Most bacterial cells are many, many times smaller than eukaryotic cells. Since they have no membrane-bound internal organelles, their cellular organization also appears much simpler. Over the last decade, however, scientists have come to understand that that bacterial cells have a cytoskeleton. Jacobs-Wagner explains that bacterial homologues of tubulin (FtsZ) and actin (MreB) are critical for cell division amongst other functions. Crescentin, a bacterial counterpart of intermediate filament proteins, gives Caulobacter crescentus its crescent shape. In addition, bacteria exhibit sophisticated spatial organization; proteins can be spatially patterned and the bacterial chromosome forms an organized structure that locates genes at specific positions in the cell.
In her second lecture, Jacobs-Wagner tells us about research in her lab into how bacterial chromosomal DNA is segregated. For distances as small as those found in a bacterial cell, diffusion can successfully distribute high copy number molecules throughout the cell. However, diffusion cannot effectively separate 2 chromosomes such that after cell division each daughter cell is likely to have one chromosome. To do this job, bacteria have evolved a partitioning system called ParABS. Jacobs-Wagner describes the how the ParABS system works to separate chromosomal DNA in C. crescentus.
Christine Jacobs-Wagner received her BS in biochemistry from the University of Liège in Belgium and her PhD from the University of Liège and the Karolinska Institute. As a post-doctoral fellow she worked with Lucy Shapiro at Stanford University. In 2001, Jacobs-Wagner moved to Yale University where she is currently a Professor of Molecular, Cellular and Developmental Biology and Director of the Microbial Sciences Institute. Jacobs-Wagner also has been a Howard Hughes Medical Institute Investigator since 2008. Her lab investigates the spatial and temporal organization of molecules inside bacteria and the impact of this organization on bacterial function and behavior.
Jacobs-Wagner’s pioneering research has been recognized with a Pew Scholar Award, the American Society for Cell Biology Women in Cell Biology Junior Award, and the Eli Lilly Award from the American Society of Microbiology.
- Lucy Shapiro iBioSeminar: The Dynamic Bacterial Cell
- Howard Berg iBioSeminar: Marvels of Bacterial Behavior
- Julie Huang iBioSeminar: H. Pylori Finds its Home
- Julie Theriot iBioSeminar: Cell Organization & Cell Motility
For talk 1:
Michie KA and Lowe J. (2006) Dynamic filament of the bacterial cytoskeleton. Ann Rev Biochem 75:467–92.
Ausmees N, Kuhn JR, and Jacobs-Wagner C. (2003) The Bacterial Cytoskeleton: An Intermediate Filament-like Function in Cell Shape. Cell 115:705-13.
Garner EC, Bernard R, Wang W, Zhuang X, Rudner DZ, and Mitchison T. (2011) Coupled, Circumferential Motions of the Cell Wall Synthesis Machinery and MreB Filaments in B. subtilis. Science 33:222-5.
Viollier PH, Thanbichler M, McGrath PT, West L, Meewan M, McAdams HH, and Shapiro L. (2004) Rapid and sequential movement of individual chromosomal loci to specific subcellular locations during bacterial DNA replication. Proc Natl Acad Sci U S A. 101:9257-62.
Matroule JY, Lam H, Burnette DT, and Jacobs-Wagner C. (2004) Cytokinesis monitoring during development: Rapid pole-to-pole shuttling of a signaling protein by localized kinase and phosphatase in Caulobacter. Cell 118:579-90.
Ebersbach G, Briegel A, Jensen GJ and Jacobs-Wagner C. (2008) A self-associating protein critical for chromosome attachment, division and polar organization in Caulobacter. Cell 134: 956-968.
For talk 2:
Lim HC, Surovtsev IV, Beltran BG, Huang F, Bewersdorf J and Jacobs-Wagner C. (2014) Evidence for a DNA-relay mechanism for ParABS-dependent segregation. eLife 3:e02758. DOI: 10.7554/eLife.02758.
Schofield WB, Lim HC and Jacobs-Wagner C. (2010) Cell cycle coordination and regulation of bacterial segregation dynamics by polarly localized proteins. EMBO J 29:3068-81.