Determining the intrinsic levels of ppGpp across a species and its influence on growth rate and tolerance to antibiotics

• Grant number: 23/13291-5
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: November 01, 2023
• End date: April 30, 2028
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Beny Spira
• Grantee: Felipe de Moraes Gomes
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 21/10577-0 - Biology of Bacteria and Bacteriophages Research Center, AP.CEPID

Abstract

The most fundamental feature of any microorganisms is its ability to grow. Unsurprisingly, growth rate is influenced by many different inputs, the most basic one being the concentration of the alarmone (p)ppGpp. It is reasonably well established that this small nucleotide controls growth rate mainly through an effective inhibition of stable RNA (rRNA and tRNA) synthesis. The level of (p)ppGpp in a cell varies in accordance with nutrient availability in the immediate surroundings, being higher under conditions of nutrient scarcity. However, there is some evidence that the intrinsic levels of (p)ppGpp also varies across a species. Namely, some strains constitutively produce more (p)ppGpp than others. These studies, however, have been performed either in isogenic laboratory strains or in semi-domesticated isolates that have been stored for years under non-ideal conditions in labs around the world . (p)ppGpp is also associated with bacterial tolerance to antibiotics. In this project the steady state level of (p)ppGpp and the growth rate in a non-domesticated collection of E. coli natural isolates will be assessed. In addition, we will also evaluate the tolerance of these strains towards antibiotics (b-lactams, quinolones and aminoglycosydes) in an attempt to correlate (p)ppGpp with tolerance and growth rate in a representative cross section of a species. If successful, we will develop a method that will allow the prediction of the tolerance level of a particular E. coli strain by gauging its (p)ppGpp level. Another molecule associated with bacterial tolerance and persistence is polyphosphate (polyP). We will also gauge the level of polyP in the bacterial collection. (AU)