Coordinating the Bacterial Cell Division and Dimensions by the Nucleoid

A Short Abstract in Lay Terms Coordinating the Bacterial Cell Division and Dimensions by the Nucleoid Application No. 2017004 - Arieh Zaritsky (BGU, IL) and Jaan Mannik (UT Knoxville, TN, USA) Two essential, unique macromolecular structures exist in a bacterium: chromosome, which stores the genetic information, and the shape-maintaining peptidoglycan sacculus, which protects the cell from rupturing by turgor pressure. Duplications of these two macromolecular structures must be coupled, temporally and spatially, to ensure that each daughter receives a fully functional genome during cell division. Several mechanisms have been proposed in the past that regulate this coordination in Escherichia coli. Surprisingly, these bacteria can propagate without all of them, indicating that there is an additional mechanism communicating between the nucleoid and the division machinery. Based on our preliminary data we propose that the primary signal for cell division stems either from crowding or a physical force exerted by transertional linkages, which connect DNA via nascent mRNA, ribosomes and emerging peptides to cell’s plasma membrane. These linkages appear to be highly dependent on chromosomal dynamics and organization. We also hypothesize that the division machinery is essential in determining cell diameter and hence shape. The mode by which chromosome coordinates cell division and modulates cell dimensions will be approached by (i) fluorescence microscopy of live bacterial cells in microfluidic devices that allow to mechanically and chemically perturb nucleoid organization, and (ii) the state-of-the-art peptidoglycan fine structure analysis. Our proposed project will advance understanding of the bacterial cell division cycle and shape determination. This study can also reveal new targets for anti-bacterial drugs.