Effects of Copper on Legionella pneumophila Revealed via Viability Assays and Proteomics
Authors:
Yang Song 1,2,*, Didier Mena-Aguilar 3,4, Connor L. Brown 5, William J. Rhoads 1,6, Richard F. Helm 7, Amy Pruden 1,* and Marc A. Edwards 1
Affiliation:
1Civil and Environmental Engineering, Virginia Tech, 1145 Perry St., 418 Durham Hall, Blacksburg, VA 24061, USA
2Utilities Department, 316 N. Academy St., Town of Cary, Cary, NC 27513, USA
3Biochemistry, Virginia Tech, 340 W Campus Dr, Blacksburg, VA 24060, USA
4Department of Biochemistry, University of Nebraska-Lincoln, N106, The Beadle Center, Lincoln, NE 68588, USA
5Genetics, Bioinformatics, and Computational Biology, Virginia Tech, Steger Hall, Blacksburg, VA 24061, USA
6Black & Veatch, 8400 Ward Pkwy, Kansas City, MO 64114, USA
7Department of Biochemistry, Virginia Tech, 1015 Life Science Circle, 211B Steger Hall, Blacksburg, VA 24061, USA
Description:
Cu is an antimicrobial that is commonly applied to premise (i.e., building) plumbing systems for Legionella control, but the precise mechanisms of inactivation are not well defined. Here, we applied a suite of viability assays and mass spectrometry-based proteomics to assess the mechanistic effects of Cu on L. pneumophila. Although a five- to six-log reduction in culturability was observed with 5 mg/L Cu2+ exposure, cell membrane integrity only indicated a <50% reduction. Whole-cell proteomic analysis revealed that AhpD, a protein related to oxidative stress, was elevated in Cu-exposed Legionella relative to culturable cells. Other proteins related to cell membrane synthesis and motility were also higher for the Cu-exposed cells relative to controls without Cu. While the proteins related to primary metabolism decreased for the Cu-exposed cells, no significant differences in the abundance of proteins related to virulence or infectivity were found, which was consistent with the ability of VBNC cells to cause infections. Whereas the cell-membrane integrity assay provided an upper-bound measurement of viability, an amoebae co-culture assay provided a lower-bound limit. The findings have important implications for assessing Legionella risk following its exposure to copper in engineered water systems.
Publications:
- Song, Yang, Didier Mena-Aguilar, Connor L. Brown, William J. Rhoads, Richard F. Helm, Amy Pruden, and Marc A. Edwards; Effects of Copper on Legionella pneumophila Revealed via Viability Assays and Proteomics; Pathogens, 2024 — Available in VTechWorks
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