The glutathione import system satisfies the Staphylococcus aureus nutrient sulfur requirement and promotes interspecies competition

Abstract

Sulfur is an indispensable element for proliferation of bacterial pathogens. Prior studies indicated that the human pathogen, Staphylococcus aureus utilizes glutathione (GSH) as a source of nutrient sulfur; however, mechanisms of GSH acquisition are not defined. Here, we identify a previously uncharacterized five-gene locus comprising a putative ABC-transporter and γ–glutamyl transpeptidase (ggt) that promotes S. aureus proliferation in medium supplemented with either reduced or oxidized GSH (GSSG) as the sole source of nutrient sulfur. Based on these phenotypes, we name this transporter the Glutathione import system (GisABCD). We confirm that Ggt is capable of cleaving GSH and GSSG γ–bonds and that this process is required for their use as nutrient sulfur sources. Additionally, we find that the enzyme is cell associated. Bioinformatic analyses reveal that only Staphylococcus species closely related to S. aureus encode GisABCD-Ggt homologues. Homologues are not detected in Staphylococcus epidermidis. Consequently, we establish that GisABCD-Ggt provides a competitive advantage for S. aureus over S. epidermidis in a GSH-dependent manner. Overall, this study describes the discovery of a nutrient sulfur acquisition system in S. aureus that targets GSH and promotes competition against other staphylococci commonly associated with the human microbiota.

Listeria monocytogenesutilizes glutathione and limited inorganic sulfur compounds as a source of essential L-cysteine

“…Curiously, L-cysteine auxotrophies in other pathogenic bacterial species ( S. enterica and E. coli ) confer a fitness advantage to these bacteria in certain in vivo niches (47), suggesting that the same may be true in Lm . The pathogen Staphylococcus aureus is similarly partially auxotrophic for L-cysteine, lacking an intact sulfate assimilation pathway but can utilize limited inorganic sulfur sources like thiosulfate for growth, and recent work has highlighted the importance of L-cysteine acquisition mechanisms during infection (51–53). Considering the essential role of L-cysteine for growth and virulence gene expression in Lm , it is compelling to suggest that partial L-cysteine auxotrophy is a pathoadaptive feature of Lm metabolism, representing an adaptation to a unique host environment.…”

MolEvolvR: A web-app for characterizing proteins using molecular evolution and phylogeny

“…The PSP system is a great use case to characterize using molecular evolution and phylogeny due to the variety of domain architectures, cellular localizations, and phyletic spreads of each of these protein families and operons. The PSP work, including this Lia operon use case, as well as other recent diverse biological applications [2][3][4][5][6][7][8][9][10][11] indicate that the MolEvolvR approach is invaluable in characterizing new protein families of interest in the context of evolution. Homolog data table with the best hits from all superkingdoms of life (queried across all RefSeq genomes).…”

“…This gap impedes identifying and characterizing the complete molecular systems involved in various critical cellular processes such as molecular pathogenesis, antibiotic resistance, or stress response. Several studies [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] have demonstrated the power of molecular evolution and phylogenetic analysis in determining molecular functions of such proteins. There are many individual tools [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] for protein sequence similarity searches or ortholog detection, delineating co-occurring domains (domain architectures), and building multiple sequence alignments and phylogenetic trees.…”

“…MolEvolvR is a generalized web-server of this web-app. To demonstrate its broad applicability, we have applied the approach underlying MolEvolvR to study several systems, including proteins/operons in zoonotic pathogens, e.g., nutrient acquisition systems in Staphylococcus aureus 4,5 , novel phage defense system in Vibrio cholerae 6 , surface layer proteins in Bacillus anthracis 7 , helicase operators in bacteria 8 , and internalins in Listeria spp 9 . We have included a few pre-loaded examples in MolEvolvR for users to explore in addition to help pages and FAQ.…”

Resveratrol-Encapsulated Glutathione-Modified Robust Mesoporous Silica Nanoparticles as an Antibacterial and Antibiofilm Coating Agent for Medical Devices

“…Previously, GSH has been reported to be a chemoattractant that entices bacteria to come in the close vicinity of Res_GSH@SNP and leads to cell disruption. 54 SEM images taken for the 2.5 × 2 cm 2 catheter piece showed less bacterial presence, which suggested that most of the bacteria died after the first contact with Res_GSH@SNP (Figure 8a−j). Bacterial cell migration was further supported by a bridge assay in which inoculated bacterial culture on one side of the plate (infection site) was supposed to migrate to the other side of the plate using a formed catheter bridge (2.5 × 1 cm 2 ; Figure 8k,l).…”