Project Details
Projekt
Investigation of the underlying mechanisms for the stability of mcr-1-encoding IncX4 plasmids
Applicant
Professorin Dr. Linda Falgenhauer
Subject Area
Medical Microbiology and Mycology, Hygiene, Molecular Infection Biology
Term
since 2022
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 491261247
Antibiotic-resistant bacteria are an emerging threat to humans worldwide. Particularly emerging are Extended-spectrum beta-lactamase (ESBL)- and carbapenemase-producing Gram-negative bacteria of the Enterobacteriaceae family, such as Escherichia coli and Klebsiella pneumoniae. A particular difficulty fact about these bacteria is that antibiotic resistance in these bacteria is often located on mobile elements, the so-called plasmids that can be transferred easily and quickly. Unfortunately, bacteria can acquire a number of different plasmids encoding a variety of antibiotic resistance genes. An extreme example is the mobile colistin resistance gene mcr-1 that causes resistance to the last-line antibiotic colistin. This gene is predominantly located on a particular type of plasmid, the IncX4 plasmid. It is found on every continent and in many different habitats (animal, humans, wild life, environment). It is a good example of a very successful plasmid – an epidemic plasmid.The question that this study wants to answer is why the mcr-1-encoding IncX4 plasmids are so successful. The hypothesis the applicant wants to work on in this study is that it increases the overall fitness of its host, the bacterium, and that this fitness effect is based on an interaction between plasmid-encoded genes and the bacterium itself.To prove this hypothesis, plasmid gene deletion mutants will be produced using a Lambda/Red recombineering system. The plasmid mutants will be analyzed first using different phenotypic assays, such as growth behavior, conjugation efficiency, antibiotic resistance, plasmid stability. Based on the results from these tests, up to ten mutants will be selected that depict a significant difference to the wild type plasmid. These ten mutants will be tested in deeper analyses for their change in transcriptome (= expression of all mRNAs), interaction partners of the mutated plasmid genes, and the overall fitness of the mutants in a consortium.At the end of this study we will be able to say: 1. Which plasmid genes have an effect on the fitness of the bacterial cell and 2. What is the basis of the change (results of transcriptome study). In a follow-up study to come, the aim is then to use the identified genes as new drug targets to tackle plasmid-encoded colistin resistance of Gram-negative bacteria.
DFG Programme
Research Grants
