Oral Presentation Australian Society for Microbiology Annual Scientific Meeting 2024

Cross-regulatory control of antibiotic resistance and virulence in uropathogenic Escherichia coli (104579)

Chyden Chang 1 2 3 , Minh-Duy Phan 1 2 3 , Dalton HY Ngu 1 2 , Jason J Paxman 4 , Jason KK Low 5 , Santosh Panjikar 6 7 , Steven J Hancock 1 2 , Kate M Peters 1 2 3 , Bostjan Kobe 1 2 , Begoña Heras 4 , Joel P Mackay 5 , Mark A Schembri 1 2 3
  1. School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Queensland, Australia
  2. Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Queensland, Australia
  3. Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland, Australia
  4. Department of Biochemistry and Genetics, La Trobe Institute of Molecular Science, La Trobe University, Melbourne, Victoria, Australia
  5. School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
  6. Australian Synchrotron, Melbourne, Victoria, Australia
  7. Department of Molecular Biology and Biochemistry, Monash University, Melbourne, Victoria, Australia

Transcriptional regulators of the MarR family regulate adaption of bacteria to different environments. The MarR family protein MprA controls expression of the EmrAB-TolC drug efflux pump, as well as capsule and flagella expression. While MprA is an attractive anti-virulence target due to its requirement for capsule expression, its regulon and mechanisms of transcriptional control have not been determined. Transcriptome analysis and MprA-DNA interactomics were used to define the MprA regulon in uropathogenic E. coli (UPEC). These approaches revealed a global regulatory role of MprA with 66 target genes (including 35 new genes) and 159 chromosomal DNA binding sites. We focused on nine promoters predicted to be directly regulated by MprA that collectively drive differential expression of 37 genes. Promoter-reporter plasmids validated that these promoters were regulated by MprA, and electrophoretic mobility shift assays confirmed specific binding of the MprA protein to these promoters. The novel MprA-regulated targets included a gene encoding a mucinase and genes involved in sialic acid catabolism, which were confirmed at the protein and phenotypic levels, respectively. We revealed a new role for MprA as a central activator of pathways that facilitate the scavenging of sialic acids from the host, enabling the use of exogenous sialic acids to produce a polysaccharide capsule and enhance virulence. MprA also activates sialic acid catabolism, a process that generate metabolites, nutrients and energy for bacterial survival. Finally, we solved a partial structure of MprA via X-ray crystallography, revealing a unique structure where the DNA-binding domain possesses a different positional framework compared to other MarR homologs, and thus suggesting a novel mechanism of DNA binding. In summary, this work provides new molecular understanding to explain how MprA regulates the expression of divergent pathways that control antibiotic resistance and virulence in UPEC, an pathogen of serious threat to human health.