title: Protein aggregation in E. coli : short term and long term effects of nutrient density.
abstract: During exponential growth some cells of E. coli undergo senescence mediated by asymmetric segregation of damaged components, particularly protein aggregates. We showed previously that functional cell division asymmetry in E. coli was responsive to the nutritional environment. Short term exposure as well as long term selection in low calorie environments led to greater cell division symmetry and decreased frequency of senescent cells as compared to high calorie environments. We show here that long term selection in low nutrient environment decreased protein aggregation as revealed by fluorescence microscopy and proportion of insoluble proteins. Across selection lines protein aggregation was correlated significantly positively with the RNA content, presumably indicating metabolic rate. This suggests that the effects of caloric restriction on cell division symmetry and aging in E. coli may work via altered protein handling mechanisms. The demonstrable effects of long term selection on protein aggregation suggest that protein aggregation is an evolvable phenomenon rather than being a passive inevitable process. The aggregated proteins progressively disappeared on facing starvation indicating degradation and recycling demonstrating that protein aggregation is a reversible process in E. coli.
authors.affiliation: Department of Microbiology, Abasaheb Garware College, Pune, Maharashtra, India; Department of Biology, Indian Institute of Science Education and Research, Pune, Maharashtra, India.
authors.forename: Ulfat I
authors.initials: UI
authors.lastname: Baig
authors.affiliation: Department of Microbiology, Abasaheb Garware College, Pune, Maharashtra, India.
authors.forename: Bharati J
authors.initials: BJ
authors.lastname: Bhadbhade
authors.affiliation: Department of Biology, Indian Institute of Science Education and Research, Pune, Maharashtra, India.
authors.forename: Dincy
authors.initials: D
authors.lastname: Mariyam
authors.affiliation: Department of Biology, Indian Institute of Science Education and Research, Pune, Maharashtra, India.
authors.forename: Milind G
authors.initials: MG
authors.lastname: Watve
mesh_terms: D003470:Culture Media; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D066329:Protein Aggregates; D012329:RNA, Bacterial / Q000378:metabolism; D012995:Solubility
chemical_list: D003470:Culture Media; D029968:Escherichia coli Proteins; D066329:Protein Aggregates; D012329:RNA, Bacterial