Transcription, Translation, and the Evolution of Specialists and Generalists
AUTOR(ES)
Zhong, Shaobin
FONTE
Oxford University Press
RESUMO
We used DNA microarrays to measure transcription and iTRAQ 2D liquid chromatography-mass spectrometry/mass spectrometry (a mass-tag labeling proteomic technique) to measure protein expression in 14 strains of Escherichia coli adapted for hundreds of generations to growth-limiting concentrations of either lactulose, methylgalactoside, or a 72:28 mixture of the two. The two ancestors, TD2 and TD10, differ only in their lac operons and have similar transcription and protein expression profiles. Changes in transcription and protein expression are observed at 30–250 genes depending on the evolved strain. Lactulose specialists carry duplications of the lac operon and show increased transcription and translation at lac. Methylgalactoside specialists are galS– and so constitutively transcribe and translate mgl, which encodes a transporter of methylgalactoside. However, there are two strains that carry lac duplications, are galS–, and show increased transcription and translation at both operons. One is a generalist, the other a lactulose specialist. The generalist fails to sweep to fixation because its lac+, galS+ competitor expresses the csg adhesin and sticks to the chemostat wall, thereby preventing complete washout. Transcription and translation are sometimes decoupled. Lactulose-adapted strains show increased protein expression at fru, a fructose transporter, without evidence of increased transcription. This suggests that fructose, produced by the action of β-galactosidase on lactulose, may leach from cells before being recouped. Reduced expression, at “late” flagella genes and the constitutive gat operon, is an adaptation to starvation. A comparison with two other long-term evolution experiments suggests that certain aspects of adaptation are predictable, some are characteristic of an experimental system, whereas others seem erratic.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2782325Documentos Relacionados
- Dissociation of Transcription, Translation, and Assembly of Collagen-tailed Acetylcholinesterase in Skeletal Muscle*
- The Two Forms of Karyogamy Transcription Factor Kar4p Are Regulated by Differential Initiation of Transcription, Translation, and Protein Turnover
- Coupling of rates of transcription, translation, and messenger ribonucleic acid degradation in streptomycin-dependent mutants of Escherichia coli.
- Efficient transcription, not translation, is dependent on adenovirus tripartite leader sequences at late times of infection.
- TnphoA and TnphoA' elements for making and switching fusions for study of transcription, translation, and cell surface localization.