Major
Microbiology
Advisor
Gregory, Steven
Advisor Department
Cell and Molecular Biology
Date
4-2020
Abstract
More than 35,000 people die in the United States every year from antibiotic-resistant infections. The overuse and misuse of prescribed medications is partly to blame for this crisis. When antibiotics are ineffective, infections last longer, are more severe, and are more expensive to treat. Since microorganisms are becoming increasingly resilient to clinically relevant antibiotics worldwide, researchers are actively studying novel treatments. Prokaryotic ribosomes are a major target of antibiotics. This cellular machinery is composed of two subunits (30Ss and 50Ss), and made of ribosomal RNA (rRNA) and protein. Its function is to translate mRNA messages into a chain of amino acids, which are delivered by tRNA. The proper formation of proteins is essential for all life. Understanding the function and importance of the ribosome allows us to investigate mechanisms of antibiotic resistance in our model organism Thermus thermophilus. The ribosomal protein bL27 is found in the 50S subunit. It consists of a globular domain situated on the subunit surface, and an extended tail that reaches into the peptidyltransferase active site, where peptide bond formation is catalyzed by the ribosome, and the site of action of numerous antibiotics. The close proximity of this tail to a critical active site suggests a role for this protein in ribosome structure and function. In order to test this hypothesis, we deleted rpmA, the gene encoding bL27, from T. thermophilus and replaced it with a kanamycin-resistance gene. PCR analysis was used to confirm the deletion. Surprisingly, the rpmA deletion mutant is viable, demonstrating that bL27 is dispensable indicating that it plays at most an indirect role in peptide bond formation. However, the role of this protein in organizing the structure of the active site has not been excluded, and is consistent with the slow-growth phenotype of this mutant.