Fromm Research Group has recently published a new article in the Journal of Infectiology and Epidemiology, titled; "From Silver(I) Exposure to Bacterial Defense: Focus on Sil and Cus Systems".

This article compares how Gram-negative bacteria tolerate Ag⁺ toxicity through the Sil and Cus systems, highlighting their components, efflux pathways, and structural adaptations.

Congratulations to Mr. Alexandre Bianchi and Prof. Katharina M. Fromm on this publication.

For more information: https://www.infectiologyjournal.com/articles/from-silveri-exposure-to-bacterial-defense-focus-on-sil-and-cus-systems.html

Abstract

Silver ions (Ag⁺) have been shown to possess antimicrobial properties. However, some Gram-negative bacteria have evolved sophisticated mechanisms to tolerate their toxicity. Among these, the plasmid-encoded Sil system and the chromosomal Cus system are key efflux-based resistance mechanisms. The Sil system is composed of a two-component regulator (SilS and SilR), periplasmic chaperones (SilF, SilG, and SilE), a P-type ATPase (SilP), and a tripartite efflux pump (SilABC) to sense, sequester, and export Ag⁺. SilE, a small periplasmic protein, plays a pivotal role by binding multiple Ag⁺ through histidine and methionine residues, which undergo a transition from disordered to α-helical conformations upon Ag⁺ coordination. A comparative analysis with the Cus system reveals that, while CusF and CusABC perform analogous metal-binding and efflux functions, Cus primarily targets Cu⁺ and lacks auxiliary components such as SilP and SilE. Collectively, these two systems demonstrate the adaptive strategies that bacteria have developed to regulate toxic metal ion concentrations.