Subtle genetic changes enhance virulence of methicillin resistant and sensitive Staphylococcus aureus

214

All strains of Staphylococcus aureus encode a putative copper-sensitive operon repressor (CsoR) and one other CsoR-like protein of unknown function. We show here that NWMN_1991 encodes a bona fide Cu(I)-inducible CsoR of a genetically unlinked copA-copZ copper resistance operon in S. aureus strain Newman. In contrast, an unannotated open reading frame found between NWMN_0027 and NWMN_0026 (denoted NWMN_0026.5) encodes a CsoR-like regulator that represses expression of adjacent genes by binding specifically to a pair of canonical operator sites positioned in the NWMN_0027-0026.5 intergenic region. Inspection of these regulated genes suggests a role in assimilation of inorganic sulfur from thiosulfate and vectorial sulfur transfer, and we designate NWMN_ 0026.5 as CstR (CsoR-like sulfur transferase repressor). Expression analysis demonstrates that CsoR and CstR control their respective regulons in response to distinct stimuli with no overlap in vivo. Unlike CsoR, CstR does not form a stable complex with Cu(I); operator binding is instead inhibited by oxidation of the intersubunit cysteine pair to a mixture of disulfide and trisulfide linkages by a likely metabolite of thiosulfate assimilation, sulfite. CsoR is unreactive toward sulfite under the same conditions. We conclude that CsoR and CstR are paralogs in S. aureus that function in the same cytoplasm to control distinct physiological processes.The Gram-positive opportunistic human pathogen Staphylococcus aureus is the causative agent of a wide range of hospital and community-acquired infections that are associated with significant morbidity (1). With the incidence of methicillinresistant strains increasing in previously low prevalence areas (2), new antibiotic therapies that target novel metabolic pathways are urgently needed. One approach is to target those processes that allow a pathogen to respond to environmental stresses that might change depending on the microenvironmental host niche in which the organism finds itself. Resistance to host-mediated copper killing of Escherichia coli (3), Salmonella enterica (4), and Mycobacterium tuberculosis (5, 6) and sulfur assimilation and cysteine biosynthesis in M. tuberculosis (7,8) are two such processes. S. aureus is particularly sensitive to rapid killing when exposed to copper or copper alloy surfaces, justifying this therapeutic direction (9, 10).M. tuberculosis CsoR 6 (copper-sensitive operon repressor) is a founding member of large family of regulators now known collectively to respond to Cu(I), Ni(II), and perhaps other stressors, the structural basis of which is not fully understood (11, 12). All CsoR family proteins lack a known canonical DNA binding domain and are projected to adopt the flat disc-shaped dimer of dimers homotetrameric structure characteristic of Cu(I)-sensing CsoRs, with individual dimers consisting of an antiparallel four-helix bundle flanked by a C-terminal ␣3 helix (13,14). Two cysteine residues on opposite subunits within a dimer make coordination bonds to the Cu(I) ion, with the third ...

Section: Discussionsupporting

confidence: 68%

Section: Discussionmentioning

confidence: 99%

Control of Copper Resistance and Inorganic Sulfur Metabolism by Paralogous Regulators in Staphylococcus aureus

Grossoehme

Kehl-Fie

et al. 2011

214

“…3). Cleavage of the 34-nucleotide top strand neared completion: 80 -90% was rapidly converted to a 17-nucleotide cleavage product, indicating that even if any religation did occur, the religation rate was very slow compared with the 4 The abbreviations used are: bis-Tris, bis(2-hydroxyethyl)iminotris(hydroxymethyl)methane; CHES, 2-(cyclohexylamino)ethanesulfonic acid.…”

Section: Resultsmentioning

confidence: 99%

“…It was first identified on the pI9789 plasmid in Staphylococcus aureus, which contains a variety of resistance genes (3,4). In vitro, and presumably in vivo, Sin resolves plasmid dimers in which two copies of the plasmid sequence are connected in a head-to-tail orientation (5,6).…”

mentioning

confidence: 99%

Arginine as a General Acid Catalyst in Serine Recombinase-mediated DNA Cleavage

Keenholtz¹,

Mouw²,

Boocock

et al. 2013

Background: Sin resolvase is a site-specific DNA recombinase that catalyzes phosphotransfer without the use of divalent cations. Results: Mutation of Arg-69 in the active site is partially rescued by a 3Ј phosphorothiolate substrate. Conclusion: Arg-69 is linked to protonation of the leaving group and most likely acts as a general acid catalyst. Significance: Serine recombinases employ a different catalytic strategy than most other phosphoryl transfer enzymes.

“…Bacterial Strains and Culture Conditions-S. aureus USA300 strains TCH1516 (14), LAC (15), and UAMS1182 (provided by G. Somerville at the University of Nebraska, Lincoln, NE), and USA1000 strain S. aureus ST59 (16) were used in the study. Additionally, the strains S. epidermidis ATCC35984 (17) and group A Streptococcus serotype M3 strain 4041-05 (Centers for Disease Control) were studied.…”

Section: Methodsmentioning

confidence: 99%

Novel Phenol-soluble Modulin Derivatives in Community-associated Methicillin-resistant Staphylococcus aureus Identified through Imaging Mass Spectrometry

Gonzalez

Okumura

Hollands

et al. 2012

Background: Phenol-soluble modulins (PSMs) are small peptides of Staphylococcus aureus with immunosuppressive and antimicrobial properties. Results: Imaging mass spectrometry (IMS) identified PSM derivatives with properties different from those of the parent forms. Conclusion: S. aureus generates truncated PSMs with altered antimicrobial and immunostimulatory properties and aureolysin may contribute to processing of some PSMs. Significance: Observations using the technology of IMS expand our understanding of S. aureus PSMs.