In vivo selection of functional ribosomes with variations in the rRNA-binding site of Escherichia coli ribosomal protein S8: evolutionary implications.
The highly conserved nature of rRNA sequences throughout evolution allows these molecules to be used to build philogenic trees of different species. It is unknown whether the stability of specific interactions and structural features of rRNA reflects an optimal adaptation to a functional task or an evolutionary trap. In the work reported here, we have applied an in vivo selection strategy to demonstrate that unnatural sequences do work as a functional replacement of the highly conserved binding site of ribosomal protein S8. However, growth competition experiments performed between Escherichia coli isolates containing natural and unnatural S8-binding sites showed that the fate of each isolate depended on the growth condition. In exponentially growing cells, one unnatural variant was found to be equivalent to wild type in competition experiments performed in rich media. In culture conditions leading to slow growth, however, cells containing the wild-type sequence were the ultimate winner of the competition, emphasizing that the wild-type sequence is, in fact, the most fit solution for the S8-binding site.
Moine
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UPR 9002 du Centre National de la Recherche Scientifique, Institut de Biologie Moléculaire et Cellulaire, 67084 Strasbourg, France. moine@ibmc.u-strasbg.fr
Squires
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CL
Ehresmann
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B
Ehresmann
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C
D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D001667:Binding, Competitive; D002455:Cell Division / Q000235:genetics; D003001:Cloning, Molecular; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D014644:Genetic Variation; D011485:Protein Binding; D012335:RNA, Ribosomal / Q000235:genetics / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism*; D000198:Spectinomycin / Q000494:pharmacology
D012335:RNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D011993:Recombinant Fusion Proteins; D012269:Ribosomal Proteins; C030254:ribosomal protein S8; D000198:Spectinomycin