title: A comprehensive genomic, transcriptomic and proteomic analysis of a hyperosmotic stress sensitive α-proteobacterium.
abstract: BACKGROUND
  With the aim of remaining viable, bacteria must deal with changes in environmental conditions, including increases in external osmolarity. While studies concerning bacterial response to this stress condition have focused on soil, marine and enteric species, this report is about Caulobacter crescentus, a species inhabiting freshwater oligotrophic habitats.
  
  
  RESULTS
  A genomic analysis reported in this study shows that most of the classical genes known to be involved in intracellular solute accumulation under osmotic adaptation are missing in C. crescentus. Consistent with this observation, growth assays revealed a restricted capability of the bacterium to propagate under hyperosmotic stress, and addition of the compatible solute glycine betaine did not improve bacterial resistance. A combination of transcriptomic and proteomic analyses indicated quite similar changes triggered by the presence of either salt or sucrose, including down-regulation of many housekeeping processes and up-regulation of functions related to environmental adaptation. Furthermore, a GC-MS analysis revealed some metabolites at slightly increased levels in stressed cells, but none of them corresponding to well-established compatible solutes.
  
  
  CONCLUSIONS
  Despite a clear response to hyperosmotic stress, it seems that the restricted capability of C. crescentus to tolerate this unfavorable condition is probably a consequence of the inability to accumulate intracellular solutes. This finding is consistent with the ecology of the bacterium, which inhabits aquatic environments with low nutrient concentration.
authors: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000, São Paulo, SP, Brazil. christiankohler_de@yahoo.de.|Present address: Friedrich Loeffler Institut for Medical Microbiology, Greifswald, Germany. christiankohler_de@yahoo.de.
authors: Christian
authors: C
authors: Kohler
authors: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000, São Paulo, SP, Brazil. lourenco@iq.usp.br.
authors: Rogério F
authors: RF
authors: Lourenço
authors: Institut for Microbiology, Ernst-Moritz-Arndt Universität, Greifswald, Germany. joerg.bernhardt@uni-greifswald.de.
authors: Jörg
authors: J
authors: Bernhardt
authors: Institut for Microbiology, Ernst-Moritz-Arndt Universität, Greifswald, Germany. dirkalbr@uni-greifswald.de.
authors: Dirk
authors: D
authors: Albrecht
authors: Institut for Microbiology, Ernst-Moritz-Arndt Universität, Greifswald, Germany. JuliaSchueler@gmx.de.
authors: Julia
authors: J
authors: Schüler
authors: Institut for Microbiology, Ernst-Moritz-Arndt Universität, Greifswald, Germany. hecker@uni-greifswald.de.
authors: Michael
authors: M
authors: Hecker
authors: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000, São Paulo, SP, Brazil. sulgomes@iq.usp.br.
authors: Suely L
authors: SL
authors: Gomes
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001622:Betaine / Q000494:pharmacology; D001692:Biological Transport; D016935:Caulobacter crescentus / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D005618:Fresh Water / Q000382:microbiology; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D058977:Molecular Sequence Annotation; D009994:Osmolar Concentration; D009997:Osmotic Pressure; D012965:Sodium Chloride / Q000494:pharmacology; D013312:Stress, Physiological; D013395:Sucrose / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D001622:Betaine; D012965:Sodium Chloride; D013395:Sucrose