Variation of the folding and dynamics of the Escherichia coli chromosome with growth conditions.
We examine whether the Escherichia coli chromosome is folded into a self-adherent nucleoprotein complex, or alternately is a confined but otherwise unconstrained self-avoiding polymer. We address this through in vivo visualization, using an inducible GFP fusion to the nucleoid-associated protein Fis to non-specifically decorate the entire chromosome. For a range of different growth conditions, the chromosome is a compact structure that does not fill the volume of the cell, and which moves from the new pole to the cell centre. During rapid growth, chromosome segregation occurs well before cell division, with daughter chromosomes coupled by a thin inter-daughter filament before complete segregation, whereas during slow growth chromosomes stay adjacent until cell division occurs. Image correlation analysis indicates that sub-nucleoid structure is stable on a 1 min timescale, comparable to the timescale for redistribution time measured for GFP-Fis after photobleaching. Optical deconvolution and writhe calculation analysis indicate that the nucleoid has a large-scale coiled organization rather than being an amorphous mass. Our observations are consistent with the chromosome having a self-adherent filament organization.
Department of Physics & Astronomy, Northwestern University, Evanston, IL 60208, USA. n-hadizadeh@northwestern.edu
Nastaran
N
Hadizadeh Yazdi
Calin C
CC
Guet
Reid C
RC
Johnson
John F
JF
Marko
D002455:Cell Division; D002876:Chromosomes, Bacterial / Q000737:chemistry* / Q000378:metabolism*; D004926:Escherichia coli / Q000254:growth & development* / Q000378:metabolism* / Q000502:physiology; D029968:Escherichia coli Proteins / Q000378:metabolism*; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D009698:Nucleoproteins / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013194:Staining and Labeling; D059008:Time-Lapse Imaging
D029968:Escherichia coli Proteins; D009698:Nucleoproteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins