scholarly journals Dynamic Relay of Protein-Bound Lipoic Acid in Staphylococcus aureus

2019 ◽  
Vol 201 (22) ◽  
Author(s):  
Wei Ping Teoh ◽  
Zachary J. Resko ◽  
Sarah Flury ◽  
Francis Alonzo
Keyword(s):  
Staphylococcus Aureus ◽  
Lipoic Acid ◽  
Organosulfur Compound ◽  
Metabolic Enzyme ◽  
Content Type ◽  
Evolutionarily Conserved ◽  
Enzyme Subunits ◽  
Glycine Cleavage ◽  
Branched Chain ◽  
Host Infection

ABSTRACT Staphylococcus aureus competes for myriad essential nutrients during host infection. One of these nutrients is the organosulfur compound lipoic acid, a cofactor required for the activity of several metabolic enzyme complexes. In S. aureus, these include the E2 subunits of three α-ketoacid dehydrogenases and two H proteins, GcvH of the glycine cleavage system and its paralog, GcvH-L. We previously determined that the S. aureus amidotransferase LipL is required for lipoylation of the E2 subunits of pyruvate dehydrogenase (PDH) and branched-chain 2-oxoacid dehydrogenase (BCODH) complexes. The results from this study, coupled with those from Bacillus subtilis, suggested that LipL catalyzes lipoyl transfer from H proteins to E2 subunits. However, to date, the range of LipL targets, the extent of LipL-dependent lipoic acid shuttling between lipoyl domain-containing proteins, and the importance of lipoyl relay in pathogenesis remain unknown. Here, we demonstrate that LipL uses both lipoyl-H proteins as the substrates for lipoyl transfer to all E2 subunits. Moreover, LipL facilitates lipoyl relay between E2 subunits and between H proteins, a property that potentially constitutes an adaptive response to nutrient scarcity in the host, as LipL is required for virulence during infection. Together, these observations support a role for LipL in facilitating flexible lipoyl relay between proteins and highlight the complexity of protein lipoylation in S. aureus. IMPORTANCE Protein lipoylation is a posttranslational modification that is evolutionarily conserved from bacteria to humans. Lipoic acid modifications are found on five proteins in S. aureus, four of which are components of major metabolic enzymes. In some bacteria, the amidotransferase LipL is critical for the attachment of lipoic acid to these proteins, and yet it is unclear to what extent LipL facilitates the transfer of this cofactor. We find that S. aureus LipL flexibly shuttles lipoic acid among metabolic enzyme subunits, alluding to a dynamic redistribution mechanism within the bacterial cell. This discovery exemplifies a potential means by which bacteria optimize the use of scarce nutrients when resources are limited.

scholarly journals Role of BrnQ1 and BrnQ2 in Branched-Chain Amino Acid Transport and Virulence in Staphylococcus aureus

2014 ◽  
Vol 83 (3) ◽  
pp. 1019-1029 ◽  
Author(s):  
Julienne C. Kaiser ◽  
Sameha Omer ◽  
Jessica R. Sheldon ◽  
Ian Welch ◽  
David E. Heinrichs
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Gene ◽  
Defined Medium ◽  
Infection Model ◽  
Content Type ◽  
Virulence Gene Expression ◽  
Branched Chain Amino Acid ◽  
Branched Chain

The branched-chain amino acids (BCAAs; Ile, Leu, and Val) not only are important nutrients for the growth ofStaphylococcus aureusbut also are corepressors for CodY, which regulates virulence gene expression, implicating BCAAs as an important link between the metabolic state of the cell and virulence. BCAAs are either synthesized intracellularly or acquired from the environment.S. aureusencodes three putative BCAA transporters, designated BrnQ1, BrnQ2, and BrnQ3; their functions have not yet been formally tested. In this study, we mutated all threebrnQparalogs so as to characterize their substrate specificities and their roles in growthin vitroandin vivo. We demonstrated that in the community-associated, methicillin-resistantS. aureus(CA-MRSA) strain USA300, BrnQ1 is involved in uptake of all three BCAAs, BrnQ2 transports Ile, and BrnQ3 does not have a significant role in BCAA transport under the conditions tested. Of the three, only BrnQ1 is essential for USA300 to grow in a chemically defined medium that is limited for Leu or Val. Interestingly, we observed that abrnQ2mutant grew better than USA300 in media limited for Leu and Val, owing to the fact that this mutation leads to overexpression ofbrnQ1. In a murine infection model, thebrnQ1mutant was attenuated, but in contrast,brnQ2mutants had significantly increased virulence compared to that of USA300, a phenotype we suggest is at least partially linked to enhancedin vivoscavenging of Leu and Val through BrnQ1. These data uncover a hitherto-undiscovered connection between nutrient acquisition and virulence in CA-MRSA.

scholarly journals MsaB and CodY Interact To RegulateStaphylococcus aureusCapsule in a Nutrient-Dependent Manner

2018 ◽  
Vol 200 (17) ◽  
Author(s):  
Justin L. Batte ◽  
Gyan S. Sahukhal ◽  
Mohamed O. Elasri
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Nutrient Sensing ◽  
Nutrient Concentrations ◽  
Dependent Manner ◽  
Regulatory Relationship ◽  
Content Type ◽  
Capsule Production ◽  
Branched Chain ◽  
Complex Regulatory Network

ABSTRACTStaphylococcus aureushas a complex regulatory network for controlling the production of capsule polysaccharide. InS. aureus, capsule production is controlled by several regulators in response to various environmental stimuli. Previously, we described MsaB as a new regulator that specifically binds to thecappromoter in a growth phase- or nutrient-dependent manner. In addition to MsaB, several other regulators have also been shown to bind the same region. In this study, we examined the interactions between MsaB and other nutrient-sensing regulators (CodY and CcpE) with respect to binding to thecappromoter in a nutrient-dependent manner. We observed thatmsaABCRandccpEinteract in a complex fashion to regulate capsule production. However, we confirmed thatccpEdoes not bindcapdirectly. We also defined the regulatory relationship betweenmsaABCRand CodY. When nutrients (branched-chain amino acids) are abundant, CodY binds to the promoter region of thecapoperon and represses its transcription. However, when nutrient concentrations decrease, MsaB, rather than CodY, binds to thecappromoter. Binding of MsaB to thecappromoter activates transcription of thecapoperon. We hypothesize that this same mechanism may be used byS. aureusto regulate other virulence factors.IMPORTANCEFindings from this study define the mechanism of regulation of capsule production inStaphylococcus aureus. Specifically, we show that two key regulators, MsaB and CodY, coordinate their functions to control the expression of capsule in response to nutrients.S. aureusfine-tunes the production of capsule by coordinating the activity of several regulators and by sensing nutrient levels. This study demonstrates the importance of incorporating multiple inputs prior to the expression of costly virulence factors, such as capsule.

scholarly journals Assembly of Lipoic Acid on Its Cognate Enzymes: an Extraordinary and Essential Biosynthetic Pathway

2016 ◽  
Vol 80 (2) ◽  
pp. 429-450 ◽  
Author(s):  
John E. Cronan
Keyword(s):  
Lipoic Acid ◽  
Biosynthetic Pathway ◽  
Sequence Similarity ◽  
Pfam Family ◽  
Glycine Cleavage System ◽  
Content Type ◽  
Metabolism Enzymes ◽  
Glycine Cleavage ◽  
State Of Affairs ◽  
Eukaryotic Organisms

SUMMARYAlthough the structure of lipoic acid and its role in bacterial metabolism were clear over 50 years ago, it is only in the past decade that the pathways of biosynthesis of this universally conserved cofactor have become understood. Unlike most cofactors, lipoic acid must be covalently bound to its cognate enzyme proteins (the 2-oxoacid dehydrogenases and the glycine cleavage system) in order to function in central metabolism. Indeed, the cofactor is assembled on its cognate proteins rather than being assembled and subsequently attached as in the typical pathway, like that of biotin attachment. The first lipoate biosynthetic pathway determined was that ofEscherichia coli, which utilizes two enzymes to form the active lipoylated protein from a fatty acid biosynthetic intermediate. Recently, a more complex pathway requiring four proteins was discovered inBacillus subtilis, which is probably an evolutionary relic. This pathway requires the H protein of the glycine cleavage system of single-carbon metabolism to form active (lipoyl) 2-oxoacid dehydrogenases. The bacterial pathways inform the lipoate pathways of eukaryotic organisms. Plants use theE. colipathway, whereas mammals and fungi probably use theB. subtilispathway. The lipoate metabolism enzymes (except those of sulfur insertion) are members of PFAM family PF03099 (the cofactor transferase family). Although these enzymes share some sequence similarity, they catalyze three markedly distinct enzyme reactions, making the usual assignment of function based on alignments prone to frequent mistaken annotations. This state of affairs has possibly clouded the interpretation of one of the disorders of human lipoate metabolism.

scholarly journals Host Fatty Acid Utilization by Staphylococcus aureus at the Infection Site

mBio ◽  
2020 ◽  
Vol 11 (3) ◽  
Author(s):  
Matthew W. Frank ◽  
Jiangwei Yao ◽  
Justin L. Batte ◽  
Jessica M. Gullett ◽  
Chitra Subramanian ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Fatty Acid ◽  
Molecular Species ◽  
De Novo ◽  
New Drugs ◽  
Pentadecanoic Acid ◽  
Infection Site ◽  
Wild Type ◽  
Content Type ◽  
Branched Chain

ABSTRACT Staphylococcus aureus utilizes the fatty acid (FA) kinase system to activate exogenous FAs for membrane synthesis. We developed a lipidomics workflow to determine the membrane phosphatidylglycerol (PG) molecular species synthesized by S. aureus at the thigh infection site. Wild-type S. aureus utilizes both host palmitate and oleate to acylate the 1 position of PG, and the 2 position is occupied by pentadecanoic acid arising from de novo biosynthesis. Inactivation of FakB2 eliminates the ability to assimilate oleate and inactivation of FakB1 reduces the content of saturated FAs and enhances oleate utilization. Elimination of FA activation in either ΔfakA or ΔfakB1 ΔfakB2 mutants does not impact growth. All S. aureus strains recovered from the thigh have significantly reduced branched-chain FAs and increased even-chain FAs compared to that with growth in rich laboratory medium. The molecular species pattern observed in the thigh was reproduced in the laboratory by growth in isoleucine-deficient medium containing exogenous FAs. S. aureus utilizes specific host FAs for membrane biosynthesis but also requires de novo FA biosynthesis initiated by isoleucine (or leucine) to produce pentadecanoic acid. IMPORTANCE The shortage of antibiotics against drug-resistant Staphylococcus aureus has led to the development of new drugs targeting the elongation cycle of fatty acid (FA) synthesis that are progressing toward the clinic. An objection to the use of FA synthesis inhibitors is that S. aureus can utilize exogenous FAs to construct its membrane, suggesting that the bacterium would bypass these therapeutics by utilizing host FAs instead. We developed a mass spectrometry workflow to determine the composition of the S. aureus membrane at the infection site to directly address how S. aureus uses host FAs. S. aureus strains that cannot acquire host FAs are as effective in establishing an infection as the wild type, but strains that require the utilization of host FAs for growth were attenuated in the mouse thigh infection model. We find that S. aureus does utilize host FAs to construct its membrane, but host FAs do not replace the requirement for pentadecanoic acid, a branched-chain FA derived from isoleucine (or leucine) that predominantly occupies the 2 position of S. aureus phospholipids. The membrane phospholipid structure of S. aureus mutants that cannot utilize host FAs indicates the isoleucine is a scarce resource at the infection site. This reliance on the de novo synthesis of predominantly pentadecanoic acid that cannot be obtained from the host is one reason why drugs that target fatty acid synthesis are effective in treating S. aureus infections.

scholarly journals EssE Promotes Staphylococcus aureus ESS-Dependent Protein Secretion To Modify Host Immune Responses during Infection

2016 ◽  
Vol 199 (1) ◽  
Author(s):  
Mark Anderson ◽  
Ryan Jay Ohr ◽  
Khaled A. Aly ◽  
Salvatore Nocadello ◽  
Hwan K. Kim ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Immune Responses ◽  
Bloodstream Infection ◽  
Molecular Mechanisms ◽  
Immune Cell ◽  
Interleukin 12 ◽  
Content Type ◽  
Host Immune Responses ◽  
Dependent Protein ◽  
Host Infection

ABSTRACT Staphylococcus aureus, an invasive pathogen of humans and animals, requires a specialized ESS pathway to secrete proteins (EsxA, EsxB, EsxC, and EsxD) during infection. Expression of ess genes is required for S. aureus establishment of persistent abscess lesions following bloodstream infection; however, the mechanisms whereby effectors of the ESS pathway implement their virulence strategies were heretofore not known. Here, we show that EssE forms a complex with other members of the ESS secretion pathway and its substrates, promoting the secretion of EsxA, EsxB, EsxC, EsxD, and EssD. During bloodstream infection of mice, the S. aureus essE mutant displays defects in host cytokine responses, specifically in the production of interleukin-12 (IL-12) (p40/p70) and the suppression of RANTES (CCL5), activators of TH1 T cell responses and immune cell chemotaxis, respectively. Thus, essE-mediated secretion of protein effectors via the ESS pathway may enable S. aureus to manipulate host immune responses by modifying the production of cytokines. IMPORTANCE Staphylococcus aureus and other firmicutes evolved a specialized ESS (EsxA/ESAT-6-like secretion system) pathway for the secretion of small subsets of proteins lacking canonical signal peptides. The molecular mechanisms for ESS-dependent secretion and their functional purpose are still unknown. We demonstrate here that S. aureus EssE functions as a membrane assembly platform for elements of the secretion machinery and their substrates. Furthermore, S. aureus EssE-mediated secretion contributes to the production or the suppression of specific cytokines during host infection, thereby modifying immune responses toward this pathogen.

scholarly journals Staphylococcus aureus adapts to the host nutritional landscape to overcome tissue-specific branched-chain fatty acid requirement

2021 ◽  
Vol 118 (13) ◽  
pp. e2022720118
Author(s):  
Wei Ping Teoh ◽  
Xi Chen ◽  
Irina Laczkovich ◽  
Francis Alonzo
Keyword(s):  
Fatty Acids ◽  
Staphylococcus Aureus ◽  
Fatty Acid ◽  
Lipoic Acid ◽  
Metabolic Reprogramming ◽  
Fatty Acid Binding ◽  
Branched Chain Fatty Acids ◽  
Branched Chain ◽  
Enzyme Complexes ◽  
Chain Fatty Acids

During infection, pathogenic microbes adapt to the nutritional milieu of the host through metabolic reprogramming and nutrient scavenging. For the bacterial pathogen Staphylococcus aureus, virulence in diverse infection sites is driven by the ability to scavenge myriad host nutrients, including lipoic acid, a cofactor required for the function of several critical metabolic enzyme complexes. S. aureus shuttles lipoic acid between these enzyme complexes via the amidotransferase, LipL. Here, we find that acquisition of lipoic acid, or its attachment via LipL to enzyme complexes required for the generation of acetyl-CoA and branched-chain fatty acids, is essential for bacteremia, yet dispensable for skin infection in mice. A lipL mutant is auxotrophic for carboxylic acid precursors required for synthesis of branched-chain fatty acids, an essential component of staphylococcal membrane lipids and the agent of membrane fluidity. However, the skin is devoid of branched-chain fatty acids. We showed that S. aureus instead scavenges host-derived unsaturated fatty acids from the skin using the secreted lipase, Geh, and the unsaturated fatty acid–binding protein, FakB2. Moreover, murine infections demonstrated the relevance of host lipid assimilation to staphylococcal survival. Altogether, these studies provide insight into an adaptive trait that bypasses de novo lipid synthesis to facilitate S. aureus persistence during superficial infection. The findings also reinforce the inherent challenges associated with targeting bacterial lipogenesis as an antibacterial strategy and support simultaneous inhibition of host fatty acid salvage during treatment.

scholarly journals Pseudomonas aeruginosa PA14 Enhances the Efficacy of Norfloxacin against Staphylococcus aureus Newman Biofilms

2020 ◽  
Vol 202 (18) ◽  
Author(s):  
Giulia Orazi ◽  
Fabrice Jean-Pierre ◽  
George A. O’Toole
Keyword(s):  
Cystic Fibrosis ◽  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Antimicrobial Agents ◽  
Respiratory Infections ◽  
Multiple Infection ◽  
Bacterial Biofilms ◽  
Interspecies Interactions ◽  
Chronic Infections ◽  
Content Type

ABSTRACT The thick mucus within the airways of individuals with cystic fibrosis (CF) promotes frequent respiratory infections that are often polymicrobial. Pseudomonas aeruginosa and Staphylococcus aureus are two of the most prevalent pathogens that cause CF pulmonary infections, and both are among the most common etiologic agents of chronic wound infections. Furthermore, the ability of P. aeruginosa and S. aureus to form biofilms promotes the establishment of chronic infections that are often difficult to eradicate using antimicrobial agents. In this study, we found that multiple LasR-regulated exoproducts of P. aeruginosa, including 2-heptyl-4-hydroxyquinoline N-oxide (HQNO), siderophores, phenazines, and rhamnolipids, likely contribute to the ability of P. aeruginosa PA14 to shift S. aureus Newman norfloxacin susceptibility profiles. Here, we observe that exposure to P. aeruginosa exoproducts leads to an increase in intracellular norfloxacin accumulation by S. aureus. We previously showed that P. aeruginosa supernatant dissipates the S. aureus membrane potential, and furthermore, depletion of the S. aureus proton motive force recapitulates the effect of the P. aeruginosa PA14 supernatant on shifting norfloxacin sensitivity profiles of biofilm-grown S. aureus Newman. From these results, we hypothesize that exposure to P. aeruginosa PA14 exoproducts leads to increased uptake of the drug and/or an impaired ability of S. aureus Newman to efflux norfloxacin. Surprisingly, the effect observed here of P. aeruginosa PA14 exoproducts on S. aureus Newman susceptibility to norfloxacin seemed to be specific to these strains and this antibiotic. Our results illustrate that microbially derived products can alter the ability of antimicrobial agents to kill bacterial biofilms. IMPORTANCE Pseudomonas aeruginosa and Staphylococcus aureus are frequently coisolated from multiple infection sites, including the lungs of individuals with cystic fibrosis (CF) and nonhealing diabetic foot ulcers. Coinfection with P. aeruginosa and S. aureus has been shown to produce worse outcomes compared to infection with either organism alone. Furthermore, the ability of these pathogens to form biofilms enables them to cause persistent infection and withstand antimicrobial therapy. In this study, we found that P. aeruginosa-secreted products dramatically increase the ability of the antibiotic norfloxacin to kill S. aureus biofilms. Understanding how interspecies interactions alter the antibiotic susceptibility of bacterial biofilms may inform treatment decisions and inspire the development of new therapeutic strategies.

scholarly journals Genome Sequences of a Staphylococcus aureus Clinical Isolate, Strain SMA0034-04 (UGA22), from Siaya County Referral Hospital in Siaya, Kenya

2019 ◽  
Vol 8 (17) ◽  
Author(s):  
Gary Xie ◽  
Qiuying Cheng ◽  
Hajnalka Daligault ◽  
Karen Davenport ◽  
Cheryl Gleasner ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Clinical Isolate ◽  
Referral Hospital ◽  
Genome Sequences ◽  
Content Type

Here, we report the genome sequences of a Staphylococcus aureus clinical isolate, strain SMA0034-04 (UGA22), which contains one chromosome and one plasmid. We also reveal that isolate SMA0034-04 (UGA22) contains loci in the genome that encode multiple exotoxins.

scholarly journals Exogenous Alginate Protects Staphylococcus aureus from Killing by Pseudomonas aeruginosa

2019 ◽  
Vol 202 (8) ◽  
Author(s):  
Courtney E. Price ◽  
Dustin G. Brown ◽  
Dominique H. Limoli ◽  
Vanessa V. Phelan ◽  
George A. O’Toole
Keyword(s):  
Staphylococcus Aureus ◽  
Pseudomonas Aeruginosa ◽  
Physical Space ◽  
Late Time ◽  
Protective Effects ◽  
Content Type ◽  
Alginate Production ◽  
The Impact

ABSTRACT Cystic fibrosis (CF) patients chronically infected with both Pseudomonas aeruginosa and Staphylococcus aureus have worse health outcomes than patients who are monoinfected with either P. aeruginosa or S. aureus. We showed previously that mucoid strains of P. aeruginosa can coexist with S. aureus in vitro due to the transcriptional downregulation of several toxic exoproducts typically produced by P. aeruginosa, including siderophores, rhamnolipids, and HQNO (2-heptyl-4-hydroxyquinoline N-oxide). Here, we demonstrate that exogenous alginate protects S. aureus from P. aeruginosa in both planktonic and biofilm coculture models under a variety of nutritional conditions. S. aureus protection in the presence of exogenous alginate is due to the transcriptional downregulation of pvdA, a gene required for the production of the iron-scavenging siderophore pyoverdine as well as the downregulation of the PQS (Pseudomonas quinolone signal) (2-heptyl-3,4-dihydroxyquinoline) quorum sensing system. The impact of exogenous alginate is independent of endogenous alginate production. We further demonstrate that coculture of mucoid P. aeruginosa with nonmucoid P. aeruginosa strains can mitigate the killing of S. aureus by the nonmucoid strain of P. aeruginosa, indicating that the mechanism that we describe here may function in vivo in the context of mixed infections. Finally, we investigated a panel of mucoid clinical isolates that retain the ability to kill S. aureus at late time points and show that each strain has a unique expression profile, indicating that mucoid isolates can overcome the S. aureus-protective effects of mucoidy in a strain-specific manner. IMPORTANCE CF patients are chronically infected by polymicrobial communities. The two dominant bacterial pathogens that infect the lungs of CF patients are P. aeruginosa and S. aureus, with ∼30% of patients coinfected by both species. Such coinfected individuals have worse outcomes than monoinfected patients, and both species persist within the same physical space. A variety of host and environmental factors have been demonstrated to promote P. aeruginosa-S. aureus coexistence, despite evidence that P. aeruginosa kills S. aureus when these organisms are cocultured in vitro. Thus, a better understanding of P. aeruginosa-S. aureus interactions, particularly mechanisms by which these microorganisms are able to coexist in proximal physical space, will lead to better-informed treatments for chronic polymicrobial infections.

scholarly journals CD4 T Cell Antigens from Staphylococcus aureus Newman Strain Identified following Immunization with Heat-Killed Bacteria

2012 ◽  
Vol 19 (4) ◽  
pp. 477-489 ◽  
Author(s):  
Paulraj K. Lawrence ◽  
Bachra Rokbi ◽  
Nadège Arnaud-Barbe ◽  
Eric L. Sutten ◽  
Junzo Norimine ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
T Cell ◽  
Reverse Genetics ◽  
Vaccine Development ◽  
Protein A ◽  
Cd4 T Cell ◽  
Content Type ◽  
Intramammary Infections ◽  
T Cell Antigens ◽  
Ifn Γ

ABSTRACTStaphylococcus aureusis a commensal bacterium associated with the skin and mucosal surfaces of humans and animals that can also cause chronic infection. The emergence of antibiotic-resistant strains such as methicillin-resistantS. aureus(MRSA) and strains causing chronic intramammary infections (IMI) in cows results in severe human and livestock infections. Conventional approaches to vaccine development have yielded only a few noneffective vaccines against MRSA or IMI strains, so there is a need for improved vaccine development. CD4 T lymphocytes are required for promoting gamma interferon (IFN-γ) mediated immunoglobulin isotype switching in B lymphocytes to produce high-affinity IgG antibodies and IFN-γ-mediated phagocyte activation for an effective resolution of bacterial infection. However, the lack of known CD4 T cell antigens fromS. aureushas made it difficult to design effective vaccines. The goal of this study was to identifyS. aureusproteins recognized by immune CD4 T cells. Using a reverse genetics approach, 43 antigens were selected from theS. aureusNewman strain. These included lipoproteins, proteases, transcription regulators, an alkaline shock protein, conserved-domain proteins, hemolysins, fibrinogen-binding protein, staphylokinase, exotoxin, enterotoxin, sortase, and protein A. Screening of expressed proteins for recall T cell responses in outbred, immune calves identified 13 proteins that share over 80% sequence identity among MRSA or IMI strains. These may be useful for inclusion in a broadly protective multiantigen vaccine against MRSA or IMI.

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