title: Asymmetric disposal of individual protein aggregates in Escherichia coli, one aggregate at a time.
abstract: Escherichia coli cells employ an asymmetric strategy at division, segregating unwanted substances to older poles, which has been associated with aging in these organisms. The kinetics of this process is still poorly understood. Using the MS2 coat protein fused to green fluorescent protein (GFP) and a reporter construct with multiple MS2 binding sites, we tracked individual RNA-MS2-GFP complexes in E. coli cells from the time when they were produced. Analyses of the kinetics and brightness of the spots showed that these spots appear in the midcell region, are composed of a single RNA-MS2-GFP complex, and reach a pole before another target RNA is formed, typically remaining there thereafter. The choice of pole is probabilistic and heavily biased toward one pole, similar to what was observed by previous studies regarding protein aggregates. Additionally, this mechanism was found to act independently on each disposed molecule. Finally, while the RNA-MS2-GFP complexes were disposed of, the MS2-GFP tagging molecules alone were not. We conclude that this asymmetric mechanism to segregate damage at the expense of aging individuals acts probabilistically on individual molecules and is capable of the accurate classification of molecules for disposal.
authors.affiliation: Laboratory of Biosystem Dynamics, Computational Systems Biology Research Group, Department of Signal Processing, Tampere University of Technology, Tampere, Finland.
authors.forename: Jason
authors.initials: J
authors.lastname: Lloyd-Price
authors.forename: Antti
authors.initials: A
authors.lastname: Häkkinen
authors.forename: Meenakshisundaram
authors.initials: M
authors.lastname: Kandhavelu
authors.forename: Ines J
authors.initials: IJ
authors.lastname: Marques
authors.forename: Sharif
authors.initials: S
authors.lastname: Chowdhury
authors.forename: Eero
authors.initials: E
authors.lastname: Lihavainen
authors.forename: Olli
authors.initials: O
authors.lastname: Yli-Harja
authors.forename: Andre S
authors.initials: AS
authors.lastname: Ribeiro
mesh_terms: D002455:Cell Division; D004926:Escherichia coli / Q000737:chemistry / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins