PMID:22056928
| Citation |
Guillemet, ML and Moreau, PL (2012) Activation of the cryptic PhnE permease promotes rapid adaptive evolution in a population of Escherichia coli K-12 starved for phosphate. J. Bacteriol. 194:253-60 |
|---|---|
| Abstract |
Escherichia coli K-12 suffers acetic acid stress during prolonged incubation in glucose minimal medium containing a limiting concentration of inorganic phosphate (0.1 mM P(i)), which decreases the number of viable cells from 6 × 10(8) to ≤10 CFU/ml between days 6 and 14 of incubation. Here we show that following two serial transfers into P(i)-limiting medium, evolved mutants survived prolonged incubation (≈10(7) CFU/ml on day 14 of incubation). The evolved strains that overtook the populations were generally PhnE(+), whereas the ancestral K-12 strain carries an inactive phnE allele, which prevents the transport of phosphonates. The switching in phnE occurred with a high frequency as a result of the deletion of an 8-bp repeated sequence. In a mixed culture starved for P(i) that contained the K-12 ancestral strain in majority, evolved strains grew through PhnE-dependent scavenging of probably organic phosphate esters (not phosphonates or P(i)) released by E. coli K-12 between days 1 and 3, before acetic acid excreted by E. coli K-12 reached toxic levels. The growth yield of phnE(+) strains in mixed culture was dramatically enhanced by mutations that affect glucose metabolism, such as an rpoS mutation inactivating the alternative sigma factor RpoS. The long-term viability of evolved populations was generally higher when the ancestral strain carried an inactive rather than an active phnE allele, which indicates that cross-feeding of phosphorylated products as a result of the phnE polymorphism may be essential for the spread of mutants which eventually help populations to survive under P(i) starvation conditions. |
| Links |
PubMed PMC3256660 Online version:10.1128/JB.06094-11 |
| Keywords |
Anion Transport Proteins/genetics; Anion Transport Proteins/metabolism; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Biological Evolution; Enzyme Activation; Escherichia coli K12/enzymology; Escherichia coli K12/metabolism; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Gene Expression Regulation, Bacterial/physiology; Organophosphates; Phenotype; Phosphates/metabolism; Sigma Factor/genetics; Sigma Factor/metabolism |
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