Investigating the Relationship Between 100S Ribosomes and Epigenetic Memory in Primed Cells — 50a — Jackson Dorsett, Manisha Guha, and Nicholas C. Butzin

Department of Biology and Microbiology; South Dakota State University; Brookings, SD, 57006; USA

Antibiotic-resistant bacteria are the leading cause of infectious deaths worldwide. This problem is predicted to worsen in the next ten years. However, most recurrent bacterial infections are caused by antibiotic persisters, not resisters. Resisters develop through gene mutations or horizontal gene transfer and can divide in the presence of antibiotics. However, persisters are genetically identical to the antibiotic-susceptible cells and do not divide in the presence of antibiotics. This non-dividing state of persisters allows them to survive because most antibiotics only target dividing cells. The phenotypic heterogeneity within an isogenic population enables persister cells to form, allowing them to survive antibiotic treatments much longer than antibiotic-susceptible cells. Though persisters survive without mutation, they lead to increased antibiotic usage, thereby enhancing the risk of developing resistant progenies. We recently showed that primed cells (dividing cells prepared for antibiotic stress before encountering it) are likely to develop into persisters. Through epigenetic memory, they can pass on their “prepared state” for several generations. It is currently unknown what mechanism allows for primed cell formation. A good candidate for their formation is the genes related to the 100S ribosome, a translationally inactive dimer of 70S ribosomes. The 100S ribosome has already been shown to be connected to persistence and forms in both exponential and stationary growth phases as a strategic adaptation for survival under stress. We utilized the CRISPR-Cas9 system to perform targeted E. coli knockouts of the hpf, rmf, and raiA, which are pivotal genes in forming and regulating 100S ribosomes. We will test if primed cells form when these genes are knocked out. If primed cell numbers decrease or the epigenetic memory is shortened in these mutants, it would indicate that 100S is related to primed cells. 

South Dakota State University
Nicholas C. Butzin