The amino acid sequence of Staphylococcus aureus penicillinase.
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ABSTRACT:
SUBMITTER: Ambler RP
PROVIDER: S-EPMC1172349 | biostudies-other | 1975 Nov
REPOSITORIES: biostudies-other
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Project description:1. Growth of Staphylococcus aureus (8325; alphai(-)p(+)), constitutive for the production of penicillinase, in CY medium results in about 40% of the enzyme being free in the medium. By modifying the medium, 98% of the enzyme remains cell-bound. 2. Part of this is bound ionically to the surface of the cell wall and may be liberated instantaneously by certain inorganic anions. Maximum liberation was achieved with either phosphate or arsenate, both of which showed marked pH-dependence. 3. Polyanions that do not penetrate the cell wall, such as heparin, RNA and dextran sulphate, are also effective in liberating penicillinase. 4. Polyanions added to the growth medium prevent the appearance of ionically bound penicillinase owing to their strong affinity for the sites on the cell wall required for binding of the enzyme.
| S-EPMC1270322 | biostudies-other
Project description:1. A further fraction of ;cell-bound exopenicillinase', in addition to that bound ionically to the surface of the cell wall, has been identified in Staphylococcus aureus. 2. Treatment of cells with low concentrations (0.01m) of organic anions liberates part of this exopenicillinase, such liberation being dependent on both time and temperature, but independent of an external supply of energy. 3. Tricarboxylic acids tend to be more effective than dicarboxylic or monocarboxylic, although there are large differences between ionic species even when tested at the same normalities.
| S-EPMC1270323 | biostudies-other
Project description:Staphylococcus aureus must rapidly adapt to a variety of carbon and nitrogen sources during invasion of a host. Within a staphylococcal abscess, preferred carbon sources such as glucose are limiting, suggesting that S. aureus survives through the catabolism of secondary carbon sources. S. aureus encodes pathways to catabolize multiple amino acids, including those that generate pyruvate, 2-oxoglutarate, and oxaloacetate. To assess amino acid catabolism, S. aureus JE2 and mutants were grown in complete defined medium containing 18 amino acids but lacking glucose (CDM). A mutation in the gudB gene, coding for glutamate dehydrogenase, which generates 2-oxoglutarate from glutamate, significantly reduced growth in CDM, suggesting that glutamate and those amino acids generating glutamate, particularly proline, serve as the major carbon source in this medium. Nuclear magnetic resonance (NMR) studies confirmed this supposition. Furthermore, a mutation in the ackA gene, coding for acetate kinase, also abrogated growth of JE2 in CDM, suggesting that ATP production from pyruvate-producing amino acids is also critical for growth. In addition, although a functional respiratory chain was absolutely required for growth, the oxygen consumption rate and intracellular ATP concentration were significantly lower during growth in CDM than during growth in glucose-containing media. Finally, transcriptional analyses demonstrated that expression levels of genes coding for the enzymes that synthesize glutamate from proline, arginine, and histidine are repressed by CcpA and carbon catabolite repression. These data show that pathways important for glutamate catabolism or ATP generation via Pta/AckA are important for growth in niches where glucose is not abundant, such as abscesses within skin and soft tissue infections.IMPORTANCES. aureus is a significant cause of both morbidity and mortality worldwide. This bacterium causes infections in a wide variety of organ systems, the most common being skin and soft tissue. Within a staphylococcal abscess, levels of glucose, a preferred carbon source, are limited due to the host immune response. Therefore, S. aureus must utilize other available carbon sources such as amino acids or peptides to proliferate. Our results show that glutamate and amino acids that serve as substrates for glutamate synthesis, particularly proline, function as major carbon sources during growth, whereas other amino acids that generate pyruvate are important for ATP synthesis via substrate-level phosphorylation in the Pta-AckA pathway. Our data support a model whereby certain amino acid catabolic pathways, and acquisition of those particular amino acids, are crucial for growth in niches where glucose is not abundant.
| S-EPMC5312079 | biostudies-literature
Project description:We present a general overview of the changes in the genetic expression along a time curve through the first 20 minutes after acidification to pH 4.5 of exponentially growing cultures of the food pathogenic strain Staphylococcus aureus 50583. A newly developed method for statistical significance testing was used to detect significant gene expression responses. Most responses showed an increase or decrease from time zero to 10 minutes after acidification and then generally a stabilisation in expression level from 10 to 20 min. Increased urease activity appeared to be an important factor in the acid defence along with proton excretion by NADH dehydrogenase and macromolecule repair mechanisms. Oxidative stress responses such as increased expression of thioredoxin genes and upregulation of pentose phosphate pathway genes to generate more reducing power were also induced. A general reduction in the expression of genes encoding ribosomal proteins and genes involved in nucleotide synthesis as well as fatty acid and lipoprotein metabolism reflected the lowered growth rate after acidification. The pH shock did not appear to trigger major virulence responses or biofilm formation. The metal ion regulation and transport was affected by the acid shock and production of several cofactors such as molybdopterin was increased. Many of the presented observations could be explained, while some represent still unknown mechanisms. The patterns of regulation were confirmed by real time reverse transcriptase PCR. Together these results showed the main responses of S. aureus and will be a good starting point for future more specific in-depth studies of specific gene responses in conjunction with acid stress defence of S. aureus. Keywords: Time course, stress response
2007-07-29 | GSE7273 | GEO
Project description:A deltalike toxin produced by a clinical isolate of Staphylococcus epidermidis was purified, and the amino acid sequence was determined. The toxin molecule consisted of 25 amino acid residues and shared a high degree of molecular homology with delta toxin purified from a Staphylococcus aureus human isolate.
| S-EPMC258650 | biostudies-other
Project description:1. Amino acid metabolism and protein synthesis in a Staphylococcus aureus mutant strain that requires pyrithiamine for optimum growth were studied and compared with those in the thiamine-requiring parent S. aureus. 2. The mutant strain utilized amino acids at a higher rate than did the parent strain. The utilization of glutamic acid, serine and glycine was much stimulated in the mutant strain. 3. The rate of oxidation of glutamic acid, aspartic acid, isoleucine and glycine was higher in the mutant strain. 4. The mutant strain contained serine, glycine, tyrosine, glutamic acid, aspartic acid, arginine and histidine as free amino acids, whereas the parent strain possessed lysine, arginine, histidine, aspartic acid and glutamic acid. 5. The mutant strain possessed slightly higher glutamate-oxalo-acetate transaminase activity, whereas the activities of glutamate-pyruvate transaminase were similar in both strains. 6. The incorporation of (14)C from [2-(14)C]-acetate into individual amino acids of the cell protein was greater in the mutant strain. 7. The incorporation of (14)C-labelled amino acids into the cell proteins of the mutant strain was not much different from that in the parent strain. 8. Induction of beta-d-galactosidase in the mutant strain did not occur, whereas induction of this enzyme is possible in the parent strain. Thiamine or pyrithiamine has no direct effect on the induction of beta-d-galactosidase.
| S-EPMC1271229 | biostudies-other
Project description:Staphylococcus aureus is a human commensal bacterium and opportunistic pathogen. Chronicity of S. aureus infection has been linked to bacterial survival within host cells including macrophages. Bacteria recovered from the intracellular milieu often form small colony variants (SCV) which are growing slowly, show reduced virulence factor production and are more resistant to antibiotics. Branched chain amino acids (BCAA) are an important class of nutrients for S. aureus. We therefore tested if components of BCAA biosynthesis or transport would alter the outcome of macrophage infection. We found that S. aureus mutants in the BCAA transporter BrnQ1 survived experimental infection of primary human macrophages for the complete duration of the 28 day experiments. Since phenotypic differences between brnQ1 mutants and wild-type bacteria occurred around 10 h p.i., we performed dual RNA-seq by which we determined the transcriptomes of both, pathogen and macrophage host, simultaneously. Our data indicate that at that time transcriptomic changes exclusively are governed by the internalized pathogen. The differential analysis of S. aureus WT and its isogenic brnQ1 mutant surprisingly demonstrated a dysregulation of iron-dependently regulated genes.
2023-06-28 | GSE235929 | GEO
Project description:Genome-wide transcriptional profiling studies of the growth of bacteria with antimicrobial agents often reveals aspects of the drug-specific protective bacterial response. Fusidic acid is a steroid antimicrobial that inhibits protein synthesis by interfering with the release of elongation factor G (EF-G) after it has functioned in the translocation step. Two hundred and seventy two genes were both up- and down-regulated in a fusidic acid-susceptible strain of Staphylococcus aureus following challenge with 2 mg/L-1 fusidic acid for 15 min. Many genes altered by fusidic acid challenge are associated with protein synthesis such as fusA, which encodes EF-G which was up-regulated following exposure to the drug. The Staphylococcus microarray meta-database which curates and compares S. aureus transcriptome data revealed that the fusidic acid stimulon has the greatest overlap with the S. aureus cold shock- and stringent-responses. Six out of 9 autolysin genes making up the two component YycFG regulon (ssaA1-ssaA4, isaA and sceD) were also upregulated by fusidic acid; as were a carboxylesterase (est) and two putative Emr-Qac-like multidrug efflux pumps (emr-qac1 and emr-qac2). Genes down-regulated by fusidic acid induction encode a putative secreted acid phosphatase (sapS) and a number of protease genes (yjbG1, yjbG2, htrA1 and htrA2). Transcriptional analysis in conjunction with mutant fusidic acid susceptibility experiments revealed that th45 e virulence gene regulatory agr operon, a YycFG controlled peptidoglycan hydrolase gene isaA and the proteases htrA1 and htrA2 are required for the expression of wild-type levels of fusidic acid susceptibility.
2008-08-25 | GSE12210 | GEO
Project description:Staphylococcus aureus is a ubiquitous bacterial pathogen that is the causative agent of numerous acute and chronic infections. S. aureus colonizes the anterior nares of a significant portion of the healthy adult population, but the mechanisms of colonization remain incompletely defined. Sialic acid (N-acetylneuraminic acid [Neu5Ac]) is a bioavailable carbon and nitrogen source that is abundant on mucosal surfaces and in secretions in the commensal environment. Our findings demonstrate that Neu5Ac can serve as an S. aureus carbon source, and we have identified a previously uncharacterized chromosomal locus (nan) that is required for Neu5Ac utilization. Molecular characterization of the nan locus indicates that it contains five genes, organized into four transcripts, and the genes were renamed nanE, nanR, nanK, nanA, and nanT. Initial studies with gene deletions indicate that nanT, predicted to encode the Neu5Ac transporter, and nanA and nanE, predicted to encode catabolic enzymes, are essential for growth on Neu5Ac. Furthermore, a nanE deletion mutant exhibits a growth inhibition phenotype in the presence of Neu5Ac. Transcriptional fusions and Northern blot analyses indicate that NanR represses the expression of both the nanAT and nanE transcripts, which can be relieved with Neu5Ac. Electrophoretic mobility studies demonstrate that NanR binds to the nanAT and nanE promoter regions, and the Neu5Ac catabolic intermediate N-acetylmannosamine-6-phosphate (ManNAc-6P) relieves NanR promoter binding. Taken together, these data indicate that the nan gene cluster is essential for Neu5Ac utilization and may perform an important function for S. aureus survival in the host.
| S-EPMC3624546 | biostudies-literature
Project description:The branched-chain amino acids (BCAAs) are vital to both growth and virulence of the human pathogen Staphylococcus aureus. In addition to supporting protein synthesis, the BCAAs serve as precursors for branched-chain fatty acids (BCFAs), which are predominant membrane fatty acids, and, in association with the global regulatory protein CodY, the BCAAs are key co-regulators of virulence factors. Despite these critical functions, S. aureus represses Leu and Val synthesis, instead preferring to acquire them from the extracellular milieu. We previously identified BrnQ1 as a BCAA transporter, yet a brnQ1 mutant remained capable of BCAA acquisition. Here, we describe BcaP as an additional BCAA transporter, and determine that it plays a secondary role to BrnQ1 during S. aureus growth in a chemically defined medium. Furthermore, membrane fatty acid composition analysis revealed that BrnQ1, and not BcaP, is required for transporting Leu and Val to be used for iso-BCFA synthesis. Despite a predominant role for BrnQ1 in vitro, both BrnQ1 and BcaP are required for S. aureus fitness in vivo in a hematogenous spread infection model and a nasal colonisation model. These data demonstrate the importance of BrnQ1 and BcaP for growth, environmental adaptation and virulence of S. aureus.
| S-EPMC6225994 | biostudies-literature