title: Spatial organization of bacterial transcription and translation.
abstract: In bacteria such as Escherichia coli, DNA is compacted into a nucleoid near the cell center, whereas ribosomes-molecular complexes that translate mRNAs into proteins-are mainly localized to the poles. We study the impact of this spatial organization using a minimal reaction-diffusion model for the cellular transcriptional-translational machinery. Although genome-wide mRNA-nucleoid segregation still lacks experimental validation, our model predicts that [Formula: see text] of mRNAs are segregated to the poles. In addition, our analysis reveals a "circulation" of ribosomes driven by the flux of mRNAs, from synthesis in the nucleoid to degradation at the poles. We show that our results are robust with respect to multiple, biologically relevant factors, such as mRNA degradation by RNase enzymes, different phases of the cell division cycle and growth rates, and the existence of nonspecific, transient interactions between ribosomes and mRNAs. Finally, we confirm that the observed nucleoid size stems from a balance between the forces that the chromosome and mRNAs exert on each other. This suggests a potential global feedback circuit in which gene expression feeds back on itself via nucleoid compaction.
authors.affiliation: Joseph Henry Laboratories of Physics, Princeton University, Princeton, NJ 08544; Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544; Laboratoire Physico-Chimie Curie, Institut Curie, CNRS UMR168, 75005 Paris, France;
authors.forename: Michele
authors.initials: M
authors.lastname: Castellana
authors.affiliation: Department of Molecular Biology, Princeton University, Princeton, NJ 08544.
authors.forename: Sophia
authors.initials: S
authors.lastname: Hsin-Jung Li
authors.affiliation: Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544; wingreen@princeton.edu.
authors.forename: Ned S
authors.initials: NS
authors.lastname: Wingreen
mesh_terms: D002453:Cell Cycle; D004058:Diffusion; D004926:Escherichia coli / Q000235:genetics*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000737:chemistry; D012270:Ribosomes / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D012333:RNA, Messenger
keywords: bacteria; experiments; localization; modeling; translation