Interference with Lipoprotein Maturation Sensitizes Methicillin-Resistant Staphylococcus aureus to Human Group IIA-Secreted Phospholipase A2 and Daptomycin

J Innate Immun. 2023;15(1):333-350. doi: 10.1159/000527549. Epub 2022 Dec 6.

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) has been classified as a high priority pathogen by the World Health Organization underlining the high demand for new therapeutics to treat infections. Human group IIA-secreted phospholipase A2 (hGIIA) is among the most potent bactericidal proteins against Gram-positive bacteria, including S. aureus. To determine hGIIA-resistance mechanisms of MRSA, we screened the Nebraska Transposon Mutant Library using a sublethal concentration of recombinant hGIIA. We identified and confirmed the role of lspA, encoding the lipoprotein signal peptidase LspA, as a new hGIIA resistance gene in both in vitro assays and an infection model in hGIIA-transgenic mice. Increased susceptibility of the lspA mutant was associated with enhanced activity of hGIIA on the cell membrane. Moreover, lspA deletion increased susceptibility to daptomycin, a last-resort antibiotic to treat MRSA infections. MRSA wild type could be sensitized to hGIIA and daptomycin killing through exposure to LspA-specific inhibitors globomycin and myxovirescin A1. Analysis of >26,000 S. aureus genomes showed that LspA is highly sequence-conserved, suggesting universal application of LspA inhibition. The role of LspA in hGIIA resistance was not restricted to MRSA since Streptococcus mutans and Enterococcus faecalis were also more hGIIA-susceptible after lspA deletion or LspA inhibition, respectively. Overall, our data suggest that pharmacological interference with LspA may disarm Gram-positive pathogens, including MRSA, to enhance clearance by innate host defense molecules and clinically applied antibiotics.

Keywords: Daptomycin; Host defense; Human group IIA-secreted phospholipase A2; Lipoprotein; Staphylococcus aureus.

MeSH terms

  • Animals
  • Anti-Bacterial Agents / pharmacology
  • Daptomycin* / pharmacology
  • Humans
  • Lipoproteins
  • Methicillin-Resistant Staphylococcus aureus*
  • Mice
  • Phospholipases A2, Secretory*
  • Staphylococcal Infections* / drug therapy
  • Staphylococcus aureus

Substances

  • Daptomycin
  • Anti-Bacterial Agents
  • Lipoproteins
  • Phospholipases A2, Secretory

Grants and funding

This work was supported by grants to Gérard Lambeau from the Centre National de la Recherche Scientifique (CNRS), the Fondation Jean Valade/Fondation de France (Award FJV_FDF-00112090), the National Research Agency (grants MNaims (ANR-17-CE17-0012-01), AirMN (ANR-20-CE14-0024-01)) and “Investments for the Future” Laboratory of Excellence SIGNALIFE, a network for innovation on signal transduction pathways in life sciences (ANR-11-LABX-0028-01 and ANR-15-IDEX-01), and the Fondation de la Recherche Médicale (DEQ20180339193L) and were used in relation to hGIIA experiments. Part of this work was supported by “Fondation Air Liquide” (Grant: S-CM19006) granted to Lhousseine Touqui to perform studies focused on the role of hGIIA in mouse survival. This study was supported by project 91713303 of the Vidi research program to Nina M. van Sorge and Vincent P. van Hensbergen and 09150181910001 of the Vici research program to Nina M. van Sorge and Marieke M. Kuijk, which is financed by the Dutch Research Council (NWO) to perform all other experiments. None of the sponsors was involved in the design, analysis, interpretation, or preparation of the data presented in the manuscript.