Mechanisms of DNA segregation and remodelling

 Marcelo NOLLMANN

 CBS - UMR 5048/U 1054

 29, rue de Navacelles, 34090 Montpellier

Phone: +33 4 67 41 79 12

Email: marcelo.nollmann@cbs.cnrs.fr

Website

Our group investigates the mechanisms by which DNA is organized and segregated in the cell by novel, state-of-the-art single-molecule and super-resolution methodologies. Specifically, we are interested in the segregation of DNA during bacterial cell division and in the mechanisms involved in higher-order organization of bacterial and eukaryotic chromosomes.
Sporulation is a developmental process triggered by adverse external conditions. During sporulation, a special type of cell division takes place, in which cells divide asymmetrically and segregate their entire genome into a small cellular compartment (forespore). This process involves the DNA translocase SpoIIIE, a AAA+ motor protein that assembles at the sporulation septum and rapidly translocates the chromosome (~3 Mbp) from the mother cell into the forespore by using the energy of ATP hydrolysis (Ptacin et al., 2008). SpoIIIE is closely related to the Escherichia coli (E.coli) DNA translocase FtsK, a motor that coordinates chromosome segregation and cell division by transferring chromosomal DNA between daughter cells (Ptacin et al., 2006). Recently, we showed that: (1) the mechanism of SRS recognition by SpoIIIE relies on a process involving passive diffusion and target motor activation (Cattoni, et al. 2013a, Cattoni, et al. 2013b); (2) SpoIIIE is part of the vegetative and sporulation division machinery and packages DNA through a pre-formed aqueous channel traversing the sporulation septum (Fiche, et al., 2013; Cattoni, et al. 2012).
In addition, we are investigating the organization of the bacterial and eukaryotic genomes in model bacteria and Drosophila by using super-resolution and advanced microscopies.

Keywords: Chromosome, bacterial division, nuclear organization, single-molecule, super-resolution

 Main publications :

• Bacterial partition complexes segregate within the volume of the nucleoid.​ Antoine Le Gall, Diego I. Cattoni, Baptiste Guilhas, Céline Mathieu-Demazière, Laura Oudjedi, Jean-Bernard Fiche, Jérôme Rech, Sara Abrahamsson, Heath Murray, Jean-Yves Bouet, Marcelo Nollmann. Nature Communications, in press.
• Astigmatic multifocus microscopy enables deep 3D super-resolved imaging. Laura Oudjedi, Jean-Bernard Fiche, Sara Abrahamsson, Laurent Mazenq, Aurélie Lecestre, Pierre-François Calmon, Aline Cerf, and Marcelo Nöllmann. Biomedical Optics Express, 2016, in press.
• Condensin- and Replication-Mediated Bacterial Chromosome Folding and Origin Condensation Revealed by Hi-C and Super-resolution Imaging. Marbouty*, M., Le Gall*, A., Cattoni, D. I., Cournac, A., Koh, A., Fiche, J.-B., Mozziconacci, J., Murray, H., Koszul^, R. & Nollmann, M.  Molecular Cell 59 (4): 588-602, 20 August 2015.
• Stochastic Self-Assembly of ParB Proteins Builds the Bacterial DNA Segregation Apparatus Aurore Sanchez, Diego I. Cattoni, Jean-Charles Walter, Jerome Rech, Andrea Parmeggiani, Marcelo Nollmann, and Jean-Yves Bouet Cell Systems 1(2): 163-73, 26 August 2015.
• A matter of scale: how emerging technologies are redefining our view of chromosome architecture. Cattoni DI, Valeri A, Le Gall A, Nollmann M Trends in Genetics, June 2015, 31, 454–464 (2015).
• Chromatin insulator factors involved in long-range DNA interactions and their role in the folding of the Drosophila genome. Vogelmann J, Le Gall A, Stephanie Dejardin S, Allemand F, Labesse G, Cuvier O, Nègre N, Cohen-Gonsaud M, Margeat E, Nöllmann. PLoS Genetics 10(8), e1004544, 2014.
• Chromosome Segregation: Original Condensins Cattoni D.I., Le Gall A., Nöllmann M.  Current Biology 24(3):R112, Feb 2014.
• Recruitment, Assembly, and Molecular Architecture of the SpoIIIE DNA Pump Revealed by Superresolution Microscopy. Fiche JB, Cattoni DI, Diekmann N, Langerak JM, Clerte C, Royer CA, Margeat E, Doan T, Nöllmann M.  PLoS Biol. 11(5):e1001557, May 2013.
• Sequence-directed DNA export guides chromosome translocation during sporulation in Bacillus subtilis. Nollmann M and Ptacin JL, Becker EC, Cozzarelli NR, Pogliano K, Bustamante C. Nature SMB 15(5):485-93, May 2008.
• Solution structure of the Tn3 resolvase-crossover site synaptic complex. Nollmann M, He J, Byron O, Stark WM. Molecular Cell 8;16(1):127-37, Oct 2004.