Fitness and cost of E. coli regulon PHO components

• Grant number: 22/10925-0
• Support Opportunities: Scholarships in Brazil - Master
• Start date: November 01, 2022
• End date: March 31, 2024
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: Beny Spira
• Grantee: Marina Caldas Leite
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The PHO regulon is a set of genes and operons scattered along the bacterial DNA and co-regulated by a single environmental factor: the low extracellular concentration of orthophosphate (Pi). This mechanism gives bacteria an evolutionary advantage in adapting to environments poor in phosphorus, an essential nutrient for their growth. The regulation of PHO regulation is strictly dependent on a chain reaction carried out by a transcriptional regulatory protein, PhoB and a transmembrane sensory protein, PhoR, in addition to a five-protein Pi transport system, Pst. Null mutations in the genes encoding the Pst transporter, result in the constitutive expression of all PHO genes. The consequence of these mutations to the bacteria's fitness in abundance or scarcity of phosphate haven't been explored. E. coli harbors two canonical Pi transporters: the already mentioned Pst system and the symporter PitA. More recently, it has been demonstrated in our laboratory that the Phn system is also capable of capturing Pi from the medium. Preliminary studies suggests that the triple mutant ”phn ”pitA ”pst could survive or grow in the presence of Pi as the sole phosphorus source, which suggests the existence of at least one more transport of Pi.The objective of this project is to test the fitness of each PHO regulon member, in addition to constructing and characterizing the triple mutant ”pitA ”pst ”phn and testing if and how it grows in a culture medium containing Pi as the sole phosphorus source.