Parallel changes in global protein profiles during long-term experimental evolution in Escherichia coli.
Twelve populations of Escherichia coli evolved in and adapted to a glucose-limited environment from a common ancestor. We used two-dimensional protein electrophoresis to compare two evolved clones, isolated from independently derived populations after 20,000 generations. Exceptional parallelism was detected. We compared the observed changes in protein expression profiles with previously characterized global transcription profiles of the same clones; this is the first time such a comparison has been made in an evolutionary context where these changes are often quite subtle. The two methodologies exhibited some remarkable similarities that highlighted two different levels of parallel regulatory changes that were beneficial during the evolution experiment. First, at the higher level, both methods revealed extensive parallel changes in the same global regulatory network, reflecting the involvement of beneficial mutations in genes that control the ppGpp regulon. Second, both methods detected expression changes of identical gene sets that reflected parallel changes at a lower level of gene regulation. The protein profiles led to the discovery of beneficial mutations affecting the malT gene, with strong genetic parallelism across independently evolved populations. Functional and evolutionary analyses of these mutations revealed parallel phenotypic decreases in the maltose regulon expression and a high level of polymorphism at this locus in the evolved populations.
Pelosi
Ludovic
L
Laboratoire Adaptation et Pathogénie des Microorganismes, Université Joseph Fourier, Grenoble, France.
Kühn
Lauriane
L
Guetta
Dorian
D
Garin
Jérôme
J
Geiselmann
Johannes
J
Lenski
Richard E
RE
Schneider
Dominique
D
D000222:Adaptation, Physiological / Q000235:genetics; D005075:Biological Evolution; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D016680:Genome, Bacterial / Q000235:genetics; D009154:Mutation; D020543:Proteome / Q000096:biosynthesis / Q000235:genetics*; D018085:Regulon / Q000235:genetics; D013997:Time Factors
D029968:Escherichia coli Proteins; D020543:Proteome