| 1. |
- Campbell, Christopher, et al.
(författare)
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Accumulation of succinyl coenzyme a perturbs the methicillin-resistant staphylococcus aureus (Mrsa) succinylome and is associated with increased susceptibility to beta-lactam antibiotics
- 2021
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Ingår i: mBio. - : American Society for Microbiology. - 2161-2129 .- 2150-7511. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- Penicillin binding protein 2a (PBP2a)-dependent resistance to β-lactam antibiotics in methicillin-resistant Staphylococcus aureus (MRSA) is regulated by the activity of the tricarboxylic acid (TCA) cycle via a poorly understood mechanism. We report that mutations in sucC and sucD, but not other TCA cycle enzymes, negatively impact β-lactam resistance without changing PBP2a expression. Increased intracellular levels of succinyl coenzyme A (succinyl-CoA) in the sucC mutant significantly perturbed lysine succinylation in the MRSA proteome. Suppressor mutations in sucA or sucB, responsible for succinyl-CoA biosynthesis, reversed sucC mutant phenotypes. The major autolysin (Atl) was the most succinylated protein in the proteome, and increased Atl succinylation in the sucC mutant was associated with loss of autolytic activity. Although PBP2a and PBP2 were also among the most succinylated proteins in the MRSA proteome, peptidoglycan architecture and cross-linking were unchanged in the sucC mutant. These data reveal that perturbation of the MRSA succinylome impacts two interconnected cell wall phenotypes, leading to repression of autolytic activity and increased susceptibility to β-lactam antibiotics.
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| 2. |
- Conlon, Brian, et al.
(författare)
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Role for the A Domain of Unprocessed Accumulation-Associated Protein (Aap) in the Attachment Phase of the Staphylococcus epidermidis Biofilm Phenotype
- 2014
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Ingår i: Journal of Bacteriology. - : American Society for Microbiology. - 0021-9193 .- 1098-5530. ; 196:24, s. 4268-4275
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Tidskriftsartikel (refereegranskat)abstract
- The polysaccharide intercellular adhesin or the cell wall-anchored accumulation-associated protein (Aap) mediates cellular accumulation during Staphylococcus epidermidis biofilm maturation. Mutation of sortase, which anchors up to 11 proteins (including Aap) to the cell wall, blocked biofilm development by the cerebrospinal fluid isolate CSF41498. Aap was implicated in this phenotype when Western blots and two-dimensional (2D) electrophoresis revealed increased levels of the protein in culture supernatants. Unexpectedly, reduced levels of primary attachment were associated with impaired biofilm formation by CSF41498 srtA and aap mutants. In contrast to previous studies, which implicated Aap proteolytic cleavage and, specifically, the Aap B domains in biofilm accumulation, the CSF41498 Aap protein was unprocessed. Furthermore, aap appeared to play a less important role in the biofilm phenotype of S. epidermidis 1457, in which the Aap protein is processed. Anti-Aap A-domain IgG inhibited primary attachment and biofilm formation in strain CSF41498 but not in strain 1457. The nucleotide sequences of the aap gene A-domain region and cleavage site in strains CSF41498 and 1457 were identical, implicating altered protease activity in the differential Aap processing results in the two strains. These data reveal a new role for the A domain of unprocessed Aap in the attachment phase of biofilm formation and suggest that extracellular protease activity can influence whether Aap contributes to the attachment or accumulation phases of the S. epidermidis biofilm phenotype
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| 3. |
- Gallagher, Laura A., et al.
(författare)
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Impaired Alanine Transport or Exposure to D-Cycloserine Increases the Susceptibility of MRSA to beta-lactam Antibiotics
- 2020
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Ingår i: Journal of Infectious Diseases. - : OXFORD UNIV PRESS INC. - 0022-1899 .- 1537-6613. ; 221:6, s. 1006-1016
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Tidskriftsartikel (refereegranskat)abstract
- Prolonging the clinical effectiveness of beta-lactams, which remain first-line antibiotics for many infections, is an important part of efforts to address antimicrobial resistance. We report here that inactivation of the predicted D-cycloserine (DCS) transporter gene cycA resensitized methicillin-resistant Staphylococcus aureus (MRSA) to beta-lactam antibiotics. The cycA mutation also resulted in hypersusceptibility to DCS, an alanine analogue antibiotic that inhibits alanine racemase and D-alanine ligase required for D-alanine incorporation into cell wall peptidoglycan. Alanine transport was impaired in the cycA mutant, and this correlated with increased susceptibility to oxacillin and DCS. The cycA mutation or exposure to DCS were both associated with the accumulation of muropeptides with tripeptide stems lacking the terminal D-ala-D-ala and reduced peptidoglycan cross-linking, prompting us to investigate synergism between beta-lactams and DCS. DCS resensitized MRSA to beta-lactams in vitro and significantly enhanced MRSA eradication by oxacillin in a mouse bacteremia model. These findings reveal alanine transport as a new therapeutic target to enhance the susceptibility of MRSA to beta-lactam antibiotics.
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| 4. |
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| 5. |
- Zeden, Merve S., et al.
(författare)
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Metabolic reprogramming and altered cell envelope characteristics in a pentose phosphate pathway mutant increases MRSA resistance to β-lactam antibiotics
- 2023
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Ingår i: PLoS Pathogens. - : Public Library of Science (PLoS). - 1553-7366 .- 1553-7374. ; 19:7
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Tidskriftsartikel (refereegranskat)abstract
- Central metabolic pathways control virulence and antibiotic resistance, and constitute potential targets for antibacterial drugs. In Staphylococcus aureus the role of the pentose phosphate pathway (PPP) remains largely unexplored. Mutation of the 6-phosphogluconolactonase gene pgl, which encodes the only non-essential enzyme in the oxidative phase of the PPP, significantly increased MRSA resistance to β-lactam antibiotics, particularly in chemically defined media with physiologically-relevant concentrations of glucose, and reduced oxacillin (OX)-induced lysis. Expression of the methicillin-resistance penicillin binding protein 2a and peptidoglycan architecture were unaffected. Carbon tracing and metabolomics revealed extensive metabolic reprogramming in the pgl mutant including increased flux to glycolysis, the TCA cycle, and several cell envelope precursors, which was consistent with increased β-lactam resistance. Morphologically, pgl mutant cells were smaller than wild-type with a thicker cell wall and ruffled surface when grown in OX. The pgl mutation reduced resistance to Congo Red, sulfamethoxazole and oxidative stress, and increased resistance to targocil, fosfomycin and vancomycin. Levels of lipoteichoic acids (LTAs) were significantly reduced in pgl, which may limit cell lysis, while the surface charge of pgl cells was significantly more positive. A vraG mutation in pgl reversed the increased OX resistance phenotype, and partially restored wild-type surface charge, but not LTA levels. Mutations in vraF or graRS from the VraFG/GraRS complex that regulates DltABCD-mediated d-alanylation of teichoic acids (which in turn controls β-lactam resistance and surface charge), also restored wild-type OX susceptibility. Collectively these data show that reduced levels of LTAs and OX-induced lysis combined with a VraFG/GraRS-dependent increase in cell surface positive charge are accompanied by significantly increased OX resistance in an MRSA pgl mutant.
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