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>> Colloquium20120306-Meso-scale intracellular molecular-patterning in bacteria: plasmid partition to c
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| 標題 | Colloquium20120306-Meso-scale intracellular molecular-patterning in bacteria: plasmid partition to c |
| 公告單位 | 系辦公室 |
| 公告類型 | 外賓參訪與演講公告 |
| 公告對象 | |
| 公告日期 | 2012-02-29 15:20:21 |
| 置頂截止日期 | 2012-03-06 |
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| 內容 | Colloquium Department of Physics, NCU Title Meso-scale intracellular molecular-patterning in bacteria: plasmid partition to cell division septum positioning Speaker Prof. Kiyoshi Mizuuchi Laboratory of Molecular Biology, National Institutes of Health, National Institute of Diabetes, and Digestive and Kidney Diseases, USA Date 2012.3.6(Tue) Time 14:00 Place S4-625 「歡迎大學部同學參加，可獲得中大護照認證2小時」 In bacteria, a family of Walker-type ATPases are involved in self-organized dynamic molecular pattern formation that controls cell division processes. We study several of these systems by using cell-free reconstituted reaction systems. Bacterial chromosome and plasmid partition systems assure stable heritance of genomes, commonly involving a partition ATPase, “centromere”-like DNA site, and a “centromere”-binding protein that stimulates the partition ATPase, which is an ATP-dependent non-specific DNA binding protein. Plasmid P1 and F partition systems have been reconstituted using fluorescence-labeled components in a flow cell under a TIRF microscope. We will discuss the possible mechanism of plasmid partition based on our recent observations. The mid-cell localization of cell division septum in E. coli is controlled by a set of Min proteins, which limits polymerization of FtsZ, the initiator of septation, to mid-cell. MinC inhibits FtsZ polymerization, and MinC distribution on the membrane is dictated by MinD to which it binds. MinD, a homologue of partition ATPases, is an ATP-dependent membrane binding protein, and MinE associates with membrane-bound MinD and controls its ATPase. Together, membrane-bound MinD (with MinC bound to it) and MinE oscillate between the cell poles in vivo. This generates time-averaged distribution minimum of MinC at the mid-cell, assuring the cell division at the mid-cell. We study self-organized MinD/E dynamics in a reconstituted cell-free system by using TIRF microscopy. The simple reaction-diffusion models previously proposed for the Min system fail to explain the results of in vitro self-organization experiments. We will discuss recent findings that shed light on the mechanistic aspects of the reaction mechanism that contribute to the spatio-temporal coordination of the membrane association and dissociation of the proteins that produces observed dynamic patterns. |