The staphylococcal respiratory response regulator SrrAB induces ica gene transcription and polysaccharide intercellular adhesin expression, protecting Staphylococcus aureus from neutrophil killing under anaerobic growth conditions (original) (raw)
Related papers
Anaerobic Gene Expression in Staphylococcus aureus
Journal of Bacteriology, 2007
An investigation of gene expression in Staphylococcus aureus after a switch from aerobic to anaerobic growth was initiated by using the proteomic and transcriptomic approaches. In the absence of external electron acceptors like oxygen or nitrate, an induction of glycolytic enzymes was observed. At the same time the amount of tricarboxylic acid cycle enzymes was very low. NAD is regenerated by mixed acid and butanediol fermentation, as indicated by an elevated synthesis level of fermentation enzymes like lactate dehydrogenases (Ldh1 and Ldh2), alcohol dehydrogenases (AdhE and Adh), ␣-acetolactate decarboxylase (BudA1), acetolactate synthase (BudB), and acetoin reductase (SACOL0111) as well as an accumulation of fermentation products as lactate and acetate. Moreover, the transcription of genes possibly involved in secretion of lactate (SACOL2363) and formate (SACOL0301) was found to be induced. The formation of acetyl-coenzyme A or acetyl-phosphate might be catalyzed by pyruvate formate lyase, whose synthesis was found to be strongly induced as well. Although nitrate was not present, the expression of genes related to nitrate respiration (NarH, NarI, and NarJ) and nitrate reduction (NirD) was found to be upregulated. Of particular interest, oxygen concentration might affect the virulence properties of S. aureus by regulating the expression of some virulence-associated genes such as pls, hly, splC and splD, epiG, and isaB. To date, the mechanism of anaerobic gene expression in S. aureus has not been fully characterized. In addition to srrA the mRNA levels of several other regulatory genes with yet unknown functions (e.g., SACOL0201, SACOL2360, and SACOL2658) were found to be upregulated during anaerobic growth, indicating a role in the regulation of anaerobic gene expression.
Molecular Microbiology, 2010
An alignment of upstream regions of anaerobically induced genes in Staphylococcus aureus revealed the presence of an inverted repeat, corresponding to Rex binding sites in Streptomyces coelicolor. Gel shift experiments of selected upstream regions demonstrated that the redox-sensing regulator Rex of S. aureus binds to this inverted repeat. The binding sequence – TTGTGAAW4TTCACAA – is highly conserved in S. aureus. Rex binding to this sequence leads to the repression of genes located downstream. The binding activity of Rex is enhanced by NAD+ while NADH, which competes with NAD+ for Rex binding, decreases the activity of Rex. The impact of Rex on global protein synthesis and on the activity of fermentation pathways under aerobic and anaerobic conditions was analysed by using a rex-deficient strain. A direct regulatory effect of Rex on the expression of pathways that lead to anaerobic NAD+ regeneration, such as lactate, formate and ethanol formation, nitrate respiration, and ATP synthesis, is verified. Rex can be considered a central regulator of anaerobic metabolism in S. aureus. Since the activity of lactate dehydrogenase enables S. aureus to resist NO stress and thus the innate immune response, our data suggest that deactivation of Rex is a prerequisite for this phenomenon.
Molecular Microbiology, 2010
An alignment of upstream regions of anaerobically induced genes in Staphylococcus aureus revealed the presence of an inverted repeat, corresponding to Rex binding sites in Streptomyces coelicolor. Gel shift experiments of selected upstream regions demonstrated that the redox-sensing regulator Rex of S. aureus binds to this inverted repeat. The binding sequence -TTGTGAAW4TTCACAA -is highly conserved in S. aureus. Rex binding to this sequence leads to the repression of genes located downstream. The binding activity of Rex is enhanced by NAD + while NADH, which competes with NAD + for Rex binding, decreases the activity of Rex. The impact of Rex on global protein synthesis and on the activity of fermentation pathways under aerobic and anaerobic conditions was analysed by using a rex-deficient strain. A direct regulatory effect of Rex on the expression of pathways that lead to anaerobic NAD + regeneration, such as lactate, formate and ethanol formation, nitrate respiration, and ATP synthesis, is verified. Rex can be considered a central regulator of anaerobic metabolism in S. aureus. Since the activity of lactate dehydrogenase enables S. aureus to resist NO stress and thus the innate immune response, our data suggest that deactivation of Rex is a prerequisite for this phenomenon.
AraC-type regulator Rsp adapts Staphylococcus aureus gene expression to acute infection
Infection and immunity, 2015
Staphylococcus aureus is an important human pathogen that can cause two categories of severe infections. Acute infections are characterized by pronounced toxin production, while chronic infections often involve biofilm formation. However, it is poorly understood how S. aureus controls the expression of genes associated with acute versus biofilm-associated virulence. We here identified an AraC-type transcriptional regulator, Rsp, that promotes the production of key toxins while repressing major biofilm-associated genes and biofilm formation. Genome-wide transcriptional analysis and modeling of regulatory networks indicated that up-regulation of the accessory gene regulator (Agr) and down-regulation of the ica operon coding for the biofilm exopolysaccharide, polysaccharide intercellular adhesin (PIA), were central to the regulatory impact of Rsp on virulence. Notably, the Rsp protein directly bound to the agrP2 and icaADBC promoters, resulting in strongly increased levels of the Agr-c...
Infection and Immunity, 2016
Staphylococcus aureus is an important opportunistic pathogen and is the etiological agent of many hospital- and community-acquired infections. The golden pigment, staphyloxanthin, of S. aureus colonies distinguishes it from other staphylococci and related Gram-positive cocci. Staphyloxanthin is the product of a series of biosynthetic steps that produce a unique membrane-embedded C 30 golden carotenoid and is an important antioxidant. We observed that a strain with an inducible airR overexpression cassette had noticeably increased staphyloxanthin production compared to the wild-type strain under aerobic culturing conditions. Further analysis revealed that depletion or overproduction of the AirR response regulator resulted in a corresponding decrease or increase in staphyloxanthin production and susceptibility to killing by hydrogen peroxide, respectively. Furthermore, the genetic elimination of staphyloxanthin during AirR overproduction abolished the protective phenotype of increased...
Characterization of the Oxygen-Responsive NreABC Regulon of Staphylococcus aureus
Journal of Bacteriology, 2008
Here, we investigate the functionality of the oxygen-responsive nitrogen regulation system NreABC in the human pathogen Staphylococcus aureus and evaluate its role in anaerobic gene regulation and virulence factor expression. Deletion of nreABC resulted in severe impairment of dissimilatory nitrate and nitrite reduction and led to a small-colony phenotype in the presence of nitrate during anaerobic growth. For characterization of the NreABC regulon, comparative DNA microarray and proteomic analyses between the wild type and nreABC mutant were performed under anoxic conditions in the absence and presence of nitrate. A reduced expression of virulence factors was not observed in the mutant. However, both the transcription of genes involved in nitrate and nitrite reduction and the accumulation of corresponding proteins were highly decreased in the nreABC mutant, which was unable to utilize nitrate as a respiratory oxidant and, hence, was forced to use fermentative pathways. These data were corroborated by the quantification of the extracellular metabolites lactate and acetate. Using an Escherichia coli-compatible two-plasmid system, the activation of the promoters of the nitrate and nitrite reductase operons and of the putative nitrate/nitrite transporter gene narK by NreBC was confirmed. Overall, our data indicate that NreABC is very likely a specific regulation system that is essential for the transcriptional activation of genes involved in dissimilatory reduction and transport of nitrate and nitrite. The study underscores the importance of NreABC as a fitness factor for S. aureus in anoxic environments.
Journal of Bacteriology, 2019
Oxygen is used as a substrate to derive energy by the bacterial pathogen Staphylococcus aureus during infection; however, S. aureus can also grow fermentatively in the absence of oxygen. To successfully cause infection, S. aureus must tailor its metabolism to take advantage of respiratory activity. Different proteins are required for growth in the presence or absence of oxygen; therefore, when cells transition between these conditions, several proteins would be expected to become unnecessary. In this report, we show that regulated proteolysis is used to modulate energy metabolism in S. aureus . We report that the ClpCP protein complex is involved in specifically modulating aerobic respiratory growth but is dispensable for fermentative growth.
Infection and Immunity, 2007
The saeRS two-component regulatory system regulates transcription of multiple virulence factors in Staphylococcus aureus . In the present study, we demonstrated that the saePQRS region in Staphylococcus epidermidis is transcriptionally regulated in a temporal manner and is arranged in a manner similar to that previously described for S. aureus . Studies using a mouse foreign body infection model demonstrated that the virulence of strain 1457 and the virulence of a mutant, strain 1457 saeR , were statistically equivalent. However, histological analyses suggested that the polymorphonuclear neutrophil response at 2 days postinfection was significantly greater in 1457-infected mice than in 1457 saeR -infected mice, demonstrating that SaeR influences the early, acute phases of infection. Microarray analysis demonstrated that a saeR mutation affected the transcription of 65 genes (37 genes were upregulated and 28 genes were downregulated); in particular, 8 genes that facilitate growth und...
bioRxiv (Cold Spring Harbor Laboratory), 2021
Transcriptional reporters are reliable and time-tested tools to study gene regulation. In Staphylococcus aureus, β-galactosidase (lacZ)-based genetic screens are not widely used because of the necessity of selectable markers for strain construction and the production of staphyloxanthin pigment which obfuscates results. We describe a series of vectors that allow for markerless insertion of codon-optimized lacZ-based transcriptional reporters. The vectors encode for different ribosomal binding sites allowing for tailored lacZ expression. A ∆crtM::kanR deletion insertion mutant was constructed that prevents the synthesis of staphyloxanthin, thereby permitting bluewhite screening without the interference of carotenoid production. We demonstrate the utility of these vectors to monitor aerobic and anaerobic transcriptional activity. For the latter, we describe the use of a ferrocyanide-ferricyanide redox system (Fe(CN) 6 3-/4-) permitting blue-white screening in the absence of oxygen. We also describe additional reporter systems and methods for monitoring transcriptional activity during anaerobic culture including a FAD-binding fluorescent protein (EcFbFP), alpha-hemolysin (hla), or lipase (geh). The systems and methods described are compatible with vectors utilized to create and screen high-density transposon mutant libraries. Importance Staphylococcus aureus is a human pathogen and a leading cause of infectious diseaserelated illness and death worldwide. For S. aureus to successfully colonize and invade host tissues, it must tightly control the expression of genes encoding for virulence factors. Oxygen tension varies greatly at infection sites and many abscesses are devoid of oxygen. In this study, we have developed novel tools and methods to study how and when S. aureus alters transcription of genes. A key advantage to these methods and tools is that they can be utilized in the presence and absence of oxygen. A better understanding of anaerobic gene expression in S. aureus will provide important insight into the regulation of genes in low oxygen environments.
The msaABCR Operon Regulates the Response to Oxidative Stress in Staphylococcus aureus
Journal of Bacteriology, 2019
This study shows the involvement of the msaABCR operon in resisting oxidative stress by Staphylococcus aureus generated under in vitro and ex vivo conditions. We show that MsaB regulates the expression and production of a carotenoid pigment, staphyloxanthin, which is a potent antioxidant in S. aureus . We also demonstrate that MsaB regulates the ohr gene, which is involved in defending against oxidative stress generated by organic hydroperoxides. This study highlights the importance of msaABCR in the survival of S. aureus in the presence of various environmental stimuli that mainly exert oxidative stress. The findings from this study indicate the possibility that msaABCR is involved in the persistence of staphylococcal infections and therefore could be a potential antimicrobial target to overcome recalcitrant staphylococcal infections.