scholarly journals De Novo Purine Biosynthesis Is Required for Intracellular Growth of Staphylococcus aureus and for the Hypervirulence Phenotype of a purR Mutant

2020 ◽  
Vol 88 (5) ◽  
Author(s):  
Mariya I. Goncheva ◽  
Ronald S. Flannagan ◽  
David E. Heinrichs
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Metabolic Regulation ◽  
De Novo ◽  
Purine Biosynthesis ◽  
Mammalian Host ◽  
Cell Binding ◽  
Intracellular Growth ◽  
Content Type ◽  
De Novo Purine Biosynthesis

ABSTRACT Staphylococcus aureus is a noted human and animal pathogen. Despite decades of research on this important bacterium, there are still many unanswered questions regarding the pathogenic mechanisms it uses to infect the mammalian host. This can be attributed to it possessing a plethora of virulence factors and complex virulence factor and metabolic regulation. PurR, the purine biosynthesis regulator, was recently also shown to regulate virulence factors in S. aureus, and mutations in purR result in derepression of fibronectin binding proteins (FnBPs) and extracellular toxins, required for a so-called hypervirulent phenotype. Here, we show that hypervirulent strains containing purR mutations can be attenuated with the addition of purine biosynthesis mutations, implicating the necessity for de novo purine biosynthesis in this phenotype and indicating that S. aureus in the mammalian host experiences purine limitation. Using cell culture, we showed that while purR mutants are not altered in epithelial cell binding, compared to that of wild-type (WT) S. aureus, purR mutants have enhanced invasion of these nonprofessional phagocytes, consistent with the requirement of FnBPs for invasion of these cells. This correlates with purR mutants having increased transcription of fnb genes, resulting in higher levels of surface-exposed FnBPs to promote invasion. These data provide important contributions to our understanding of how the pathogenesis of S. aureus is affected by sensing of purine levels during infection of the mammalian host.

scholarly journals The de novo Purine Biosynthesis Pathway Is the Only Commonly Regulated Cellular Pathway during Biofilm Formation in TSB-Based Medium in Staphylococcus aureus and Enterococcus faecalis

2021 ◽  
Keyword(s):  
Staphylococcus Aureus ◽  
Enterococcus Faecalis ◽  
Biofilm Formation ◽  
De Novo ◽  
Purine Biosynthesis ◽  
Biosynthesis Pathway ◽  
Chronic Infections ◽  
De Novo Purine Biosynthesis ◽  
Cellular Pathways ◽  
Different Strains

Bacterial biofilms are involved in chronic infections and confer 10 to 1,000 times more resistance to antibiotics compared with planktonic growth, leading to complications and treatment failure. When transitioning from a planktonic lifestyle to biofilms, some Gram-positive bacteria are likely to modulate several cellular pathways, including central carbon metabolism, biosynthesis pathways, and production of secondary metabolites. These metabolic adaptations might play a crucial role in biofilm formation by Gram-positive pathogens such as Staphylococcus aureus and Enterococcus faecalis. Here, we performed a transcriptomic approach to identify cellular pathways that might be similarly regulated during biofilm formation in these bacteria. Different strains and biofilm-inducing media were used to identify a set of regulated genes that are common and independent of the environment or accessory genomes analyzed. Our approach highlighted that the de novo purine biosynthesis pathway was upregulated in biofilms of both species when using a tryptone soy broth-based medium but not so when a brain heart infusion-based medium was used. We did not identify other pathways commonly regulated between both pathogens. Gene deletions and usage of a drug targeting a key enzyme showed the importance of this pathway in biofilm formation of S. aureus. The importance of the de novo purine biosynthesis pathway might reflect an important need for purine during biofilm establishment, and thus could constitute a promising drug target. IMPORTANCE Biofilms are often involved in nosocomial infections and can cause serious chronic infections if not treated properly. Current anti-biofilm strategies rely on antibiotic usage, but they have a limited impact because of the biofilm intrinsic tolerance to drugs. Metabolism remodeling likely plays a central role during biofilm formation. Using comparative transcriptomics of different strains of Staphylococcus aureus and Enterococcus faecalis, we determined that almost all cellular adaptations are not shared between strains and species. Interestingly, we observed that the de novo purine biosynthesis pathway was upregulated during biofilm formation by both species in a specific medium. The requirement for purine could constitute an interesting new anti-biofilm target with a wide spectrum that could also prevent resistance evolution. These results are also relevant to a better understanding of the physiology of biofilm formation.

scholarly journals Carbocyclic substrates for de novo purine biosynthesis.

1991 ◽  
Vol 266 (25) ◽  
pp. 16699-16702
Author(s):  
D.S. Liu ◽  
C.A. Caperelli
Keyword(s):  
De Novo ◽  
Purine Biosynthesis ◽  
De Novo Purine Biosynthesis

scholarly journals Finding of Agr Phase Variants in Staphylococcus aureus

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Vishal Gor ◽  
Aya J. Takemura ◽  
Masami Nishitani ◽  
Masato Higashide ◽  
Veronica Medrano Romero ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Phase Variation ◽  
Accessory Gene ◽  
Content Type ◽  
Accessory Gene Regulator ◽  
Immune Mediated ◽  
A Minor ◽  
First Time ◽  
Phase Variants

ABSTRACT Staphylococcus aureus is an important human pathogen whose success is largely attributed to its vast arsenal of virulence factors that facilitate its invasion into, and survival within, the human host. The expression of these virulence factors is controlled by the quorum sensing accessory gene regulator (Agr) system. However, a large proportion of clinical S. aureus isolates are consistently found to have a mutationally inactivated Agr system. These mutants have a survival advantage in the host but are considered irreversible mutants. Here we show, for the first time, that a fraction of Agr-negative mutants can revert their Agr activity. By serially passaging Agr-negative strains and screening for phenotypic reversion of hemolysis and subsequent sequencing, we identified two mutational events responsible for reversion: a genetic duplication plus inversion event and a poly(A) tract alteration. Additionally, we demonstrate that one clinical Agr-negative methicillin-resistant S. aureus (MRSA) isolate could reproducibly generate Agr-revertant colonies with a poly(A) tract genetic mechanism. We also show that these revertants activate their Agr system upon phagocytosis. We propose a model in which a minor fraction of Agr-negative S. aureus strains are phase variants that can revert their Agr activity and may act as a cryptic insurance strategy against host-mediated stress. IMPORTANCE Staphylococcus aureus is responsible for a broad range of infections. This pathogen has a vast arsenal of virulence factors at its disposal, but avirulent strains are frequently isolated as the cause of clinical infections. These isolates have a mutated agr locus and have been believed to have no evolutionary future. Here we show that a fraction of Agr-negative strains can repair their mutated agr locus with mechanisms resembling phase variation. The agr revertants sustain an Agr OFF state as long as they exist as a minority but can activate their Agr system upon phagocytosis. These revertant cells might function as a cryptic insurance strategy to survive immune-mediated host stress that arises during infection.

scholarly journals Draft Genome Sequence of the Community-Associated Staphylococcus aureus Sequence Type 88 Strain LVP-7, Isolated from an Ocular Infection

2021 ◽  
Vol 10 (7) ◽  
Author(s):  
Savitha Nadig ◽  
Sneha Murthy ◽  
Muralidharan Vandanashree ◽  
Hosahalli S. Subramanya ◽  
Balasubramanian Gopal ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Genome Sequence ◽  
De Novo ◽  
Draft Genome ◽  
Sequence Type ◽  
Draft Genome Sequence ◽  
Ocular Infection ◽  
Content Type ◽  
Type V ◽  
Panton Valentine Leukocidin

ABSTRACT We report a de novo-assembled draft genome sequence of the Indian Staphylococcus aureus sequence type 88 (ST88) strain LVP-7, isolated from an ocular infection. The genome harbors a Panton-Valentine leukocidin phage, a type V staphylococcal cassette chromosome mec element, the delta-hemolysin-converting Newman phage ΦNM3, and the pathogenicity island SaPI3, encoding the superantigen enterotoxin B.

Purine metabolism in Neisseria gonorrhoeae: the requirement for hypoxanthine

1980 ◽  
Vol 26 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Stephen A. Morse ◽  
Lynne Bartenstein
Keyword(s):  
Neisseria Gonorrhoeae ◽  
Growth Medium ◽  
De Novo ◽  
Defined Medium ◽  
Purine Metabolism ◽  
Purine Biosynthesis ◽  
Free Medium ◽  
De Novo Purine Biosynthesis ◽  
Reduced Rate

Strains isolated from disseminated gonococcal infections often require hypoxanthine for growth. The biochemical bases for the requirement for hypoxanthine in strains isolated from both disseminated (Ile−Val−Arg−Hyx−Ura−phenotype) and non-disseminated (Hyx−phenotype) infections were compared. The requirement for hypoxanthine was dependent upon the composition of the growth medium. In a complete defined medium, hypoxanthine was replaced by a mixture of adenine and guanine but not by either purine alone. The addition of adenine alone inhibited gonococcal growth. This inhibition was reversed by the addition of guanine and most likely resulted from an inhibition of de novo purine biosynthesis. In a histidine-free medium, adenine replaced the hypoxanthine requirement in Ile−Val−Arg−Hyx−Ura− strains. Adenine did not replace the hypoxanthine requirement in Hyx− strains. The Ile−Val−Arg−Hyx−Ura− strains exhibited a markedly reduced rate of de novo purine biosynthesis while Hyx− strains were blocked in this pathway. In vivo concentrations of purines are important factors which may limit the intracellular or extracellular growth of these strains.

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