Invited Speaker Australian Society for Microbiology Annual Scientific Meeting 2023

The two-component regulator WalKR provides an essential link between cell wall homeostasis with DNA replication in Staphylococcus aureus (93815)

Liam K Sharkey 1 , Romain Guerillot 1 , Calum Walsh 1 , Adrianna M Turner 1 , Jean HY Lee 1 , Stephanie L Neville 1 , Stephan Klatt 1 , Sarah L Baines 1 , Torsten Seeman 1 , Hamish McWilliam 1 , Ellie Cho 2 , Fernando J Rossello 3 , Glen P Carter 1 , Benjamin P Howden 1 , Christopher A McDevitt 1 , Abderrahman Hachani 1 , Timothy P Stinear 1 , Ian R Monk 1
  1. Department of Microbiology and Immunology, The University of Melbourne at the Doherty Institute for Infection & Immunity, Melbourne, Victoria, Australia
  2. Biological Optical Microscopy Platform, Melbourne, Victoria, Australia
  3. University of Melbourne Centre for Cancer Research, Melbourne, Victoria, Australia

Among the 16 two-component systems (TCSs) in the opportunistic human pathogen Staphylococcus aureus, only WalKR is essential. Like orthologous systems in other Bacillota, S. aureus WalKR controls autolysins involved in peptidoglycan remodelling and is therefore intimately involved in cell division. However, despite the importance of WalKR in S. aureus, the basis for its essentiality is not understood and the regulon incompletely mapped. Here, we define the direct WalKR regulon using functional genomics, including ChIP-seq. Consistent with prior findings, WalKR regulates multiple autolysin genes. However, we describe for the first time that WalR directly regulates at least five essential genes involved in lipoteichoic acid synthesis (ltaS); translation (rplK); DNA compaction (hup); initiation of DNA replication (dnaA, hup); and purine nucleotide metabolism (prs). Thus, WalKR in S. aureus serves as a polyfunctional regulator that contributes to fundamental control over critical cell processes by co-ordinately linking cell wall homeostasis with purine biosynthesis, protein biosynthesis, and DNA replication. Collectively, our findings address the essentiality of this locus and highlight WalKR as a bona fide target for novel anti-staphylococcal therapeutics.