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Evolution connection: Ribosomes. Learning goals:
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Evolution connection: Ribosomes Learning goals: Students will understand that 1) some antibiotics work by attacking the ribosome, 2) tiny differences that evolved in the ribosomes of prokaryotes and eukaryotes are responsible for the specificity of those drugs towards bacterial ribosomes, 3) our mitochondria are vulnerable to such drugs because these organelles evolved via endosymbiosis from bacteria, and 4) our evolutionary history matters in our everyday lives. For the instructor: This short slide set connects the topic of cellular ribosomes to both our evolutionary history and modern medicine. Slide 9 may be skipped to save time. Throughout the notes, optional information is included in parentheses in case the instructor wants to go into more detail. To integrate these slides best, use them immediately after you’ve discussed the structure of ribosomes and their role in the cell. Alternatively, you may wish to use these slides when you discuss translation later in the semester.
Evolution connection: Ribosomes Ribosomes: An achilles heel for bacteria Petri dish photo from CDC; researcher photo from CDC/Dr. U.P. Kokko; photo of various medicines from National Institute of Health
Evolution connection: Ribosomes Why don’t antibiotics like streptomycin harm our own cells?
Evolution connection: Ribosomes Ribosomes evolved early in the history of life All ribosomes share: similar rRNA sequences small subunit that decodes mRNA large subunit that joins amino acids together The ribosome evolved back here.
Evolution connection: Ribosomes Ribosomes evolved early in the history of life Small evolutionary changes big impact ... and evolved modifications as life’s lineages diversified. The ribosome evolved back here.
Evolution connection: Ribosomes Streptomycin-like antibiotics bind to the ribosome A site antibiotic Antibiotic binds here and interferes with protein synthesis … ribosome … but not in eukaryotic ribosomes.
Evolution connection: Ribosomes Streptomycin-like antibiotics can’t bind to the eukaryotic ribosome … … because of position 1408 In the small ribosomal subunit. A G
Evolution connection: Ribosomes Streptomycin-like antibiotics can’t bind to the eukaryotic ribosome … Images provided by Joseph D. Puglisi.
Evolution connection: Ribosomes But eukaryotic mitochondrial ribosomes are vulnerable. Mitochondrion A G ribosomes
References Bokov, K., and Steinberg, S. V. (2009). A hierarchical model for evolution of 23S ribosomal RNA. Nature. 457: 977-980. Lynch, S. R., and Puglisi, J. D. (2001). Structural origins of aminoglycoside specificity for prokaryotic ribosomes. Journal of Molecular Biology. 306: 1037-1058. Pace, N. R. (1997). A molecular view of microbial diversity and the biosphere. Science. 276: 734-740. Recht, M. I., Douthwaite, S., and Puglisi, J. D. (1999). Basis for prokaryotic specificity of action of aminoglycoside antibiotics. The EMBO Journal. 18: 3133-3138. Selimoglu, E. (2007). Aminoglycoside-induced ototoxicity. Current Pharmaceutical Design. 13: 119-126.