Virtual Poster 21st Lancefield International Symposium for Streptococci and Streptococcal Diseases 2022

The copper resistome of group B Streptococcus reveals insight into the genetic basis of cellular survival during metal ion stress (#210)

Kelvin GK Goh 1 2 , Matthew J Sullivan 1 2 , Glen C Ulett 1 2
  1. School of Pharmacy and Medical Sciences, Griffith University, Gold Coast, QLD, Australia
  2. Menzies Health Institute Queensland, Griffith University, Gold Coast, QLD, Australia

In bacteria, copper (Cu) can support metabolic processes as an enzymatic cofactor but can also cause cell damage if present in excess, leading to intoxication. In group B Streptococcus (GBS) a system for control of Cu efflux based on the canonical cop operon supports survival during Cu stress. In some other bacteria, genetic systems additional to the cop operon are engaged during Cu stress and also contribute to Cu management. Here, we examined genetic systems beyond the cop operon in GBS for regions that contribute to survival of GBS in Cu stress using a forward genetic screen and probe of the entire bacterial genome. A high-density mutant library, generated using pGh9-ISS1, was used to expose GBS to Cu stress and compared to non-exposed controls en masse. Several genes were identified as essential for GBS survival in Cu stress, whereas five others constrained GBS growth in Cu stress. The genes encode varied factors including enzymes for metabolism, cell wall synthesis, transporters and global transcriptional regulators. Targeted mutation of the genes validated their roles in GBS resistance to Cu stress. Notably, several genes were also essential for resistance to Zn stress. Excepting copA, the genes identified are new to the area of bacterial metal ion intoxication. We conclude that a discrete and limited suite of genes beyond the cop operon in GBS contribute to a repertoire of mechanisms used to survive Cu stress in vitro and achieve cellular homeostasis.