<scp>R</scp>ot is a key regulator of <scp><i>S</i></scp><i>taphylococcus aureus</i> biofilm formation

Mootz, Joe M.; Benson, Meredith A.; Heim, Cortney E.; Crosby, Heidi A.; Kavanaugh, J.S.; Dunman, Paul M.; Kielian, Tammy; Torres, Victor J.; Horswill, Alexander R.

doi:10.1111/mmi.12943

Cited by 70 publications

(72 citation statements)

References 64 publications

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“…Additionally, a gene ontology analysis using GoMiner (43) identified genes in the category of pathogenesis, including proteases (spl, ssp, and aur) and toxins, as the most highly enriched category of genes that are overexpressed in the ⌬sarA mutant, consistent with previous ⌬sarA mutant transcriptomics studies (60)(61)(62)(63). Interestingly, the ⌬sarA mutant is not the only NO˙-sensitive mutant we identified that overproduces proteases; the ⌬codY and ⌬rot mutants have also been characterized as overproducers of at least several of the 10 extracellular proteases secreted by S. aureus (64)(65)(66)(67)(68)(69). SarA and Rot directly repress protease transcription, whereas CodY indirectly represses protease transcription by repressing agrA (Fig.…”

Section: Resultssupporting

confidence: 71%

Regulatory Requirements for Staphylococcus aureus Nitric Oxide Resistance

et al. 2016

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The ability of Staphylococcus aureus to resist host innate immunity augments the severity and pervasiveness of its pathogenesis. Nitric oxide (NO˙) is an innate immune radical that is critical for the efficient clearance of a wide range of microbial pathogens. Exposure of microbes to NO˙typically results in growth inhibition and induction of stress regulons. S. aureus, however, induces a metabolic state in response to NO˙that allows for continued replication and precludes stress regulon induction. The regulatory factors mediating this distinctive response remain largely undefined. Here, we employ a targeted transposon screen and transcriptomics to identify and characterize five regulons essential for NO˙resistance in S. aureus: three virulence regulons not formerly associated with NO˙resistance, SarA, CodY, and Rot, as well as two regulons with established roles, Fur and SrrAB. We provide new insights into the contributions of Fur and SrrAB during NO˙stress and show that the S. aureus ⌬sarA mutant, the most sensitive of the newly identified mutants, exhibits metabolic dysfunction and widespread transcriptional dysregulation following NO˙exposure. Altogether, our results broadly characterize the regulatory requirements for NO˙resistance in S. aureus and suggest an intriguing overlap between the regulation of NO˙resistance and virulence in this well-adapted human pathogen. IMPORTANCEThe prolific human pathogen Staphylococcus aureus is uniquely capable of resisting the antimicrobial radical nitric oxide (NO˙), a crucial component of the innate immune response. However, a complete understanding of how S. aureus regulates an effective response to NO˙is lacking. Here, we implicate three central virulence regulators, SarA, CodY, and Rot, as major players in the S. aureus NO˙response. Additionally, we elaborate on the contribution of two regulators, SrrAB and Fur, already known to play a crucial role in S. aureus NO˙resistance. Our study sheds light on a unique facet of S. aureus pathogenicity and demonstrates that the transcriptional response of S. aureus to NO˙is highly pleiotropic and intrinsically tied to metabolism and virulence regulation. The versatile Gram-positive pathogen Staphylococcus aureus is the leading cause of skin and soft tissue infections (SSTIs) in the United States but can also cause more severe illnesses, including pneumonia, osteomyelitis, endocarditis, and bacteremia (1-5). The ability of S. aureus to infect virtually every tissue of the body can be partially attributed to its extensive capacity for subverting host immunity. One unique defense of S. aureus against the immune system is resistance to nitric oxide (NO˙), a membrane-permeable radical and broad-spectrum innate immune effector required for the clearance of bacterial, viral, and fungal pathogens (6). The ability of S. aureus to continue growth in the presence of NO˙at concentrations that are inhibitory to other bacteria, including closely related staphylococci, contributes to its invasiveness and pathogenic success. For example...

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Section: Resultssupporting

confidence: 71%

Regulatory Requirements for Staphylococcus aureus Nitric Oxide Resistance

et al. 2016

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“…S. aureus biofilm studies to date have mostly been performed using commercially available rich or chemically defined media, which has provided a wealth of information about important bacterial contributors to the biofilm process, but these defined growth conditions have limited application to the host environment. In some studies, human matrix proteins have been used to aid S. aureus attachment and enhance biofilm accumulation (35)(36)(37)(38), providing a biotic substratum that better imitates a realistic host surface. Although these approaches are an improvement and likely enhance the relevance of biofilm observations, the abundance of host glycosaminoglycans in many tissues and their contribution to S. aureus biofilm formation remain mostly overlooked.…”

Section: Discussionmentioning

confidence: 99%

Hyaluronan Modulation Impacts Staphylococcus aureus Biofilm Infection

et al. 2016

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Staphylococcus aureus is a leading cause of chronic biofilm infections. Hyaluronic acid (HA) is a large glycosaminoglycan abundant in mammalian tissues that has been shown to enhance biofilm formation in multiple Gram-positive pathogens. We observed that HA accumulated in an S. aureus biofilm infection using a murine implant-associated infection model and that HA levels increased in a mutant strain lacking hyaluronidase (HysA). S. aureus secretes HysA in order to cleave HA during infection. Through in vitro biofilm studies with HA, the hysA mutant was found to accumulate increased biofilm biomass compared to the wild type, and confocal microscopy showed that HA is incorporated into the biofilm matrix. Exogenous addition of purified HysA enzyme dispersed HA-containing biofilms, while catalytically inactive enzyme had no impact. Additionally, induction of hysA expression prevented biofilm formation and also dispersed an established biofilm in the presence of HA. These observations were corroborated in the implant model, where there was decreased dissemination from an hysA mutant biofilm infection compared to the S. aureus wild type. Histopathology demonstrated that infection with an hysA mutant caused significantly reduced distribution of tissue inflammation compared to wild-type infection. To extend these studies, the impact of HA and S. aureus HysA on biofilm-like aggregates found in joint infections was examined. We found that HA contributes to the formation of synovial fluid aggregates, and HysA can disrupt aggregate formation. Taken together, these studies demonstrate that HA is a relevant component of the S. aureus biofilm matrix and HysA is important for dissemination from a biofilm infection.

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confidence: 99%

“…Because of this allelic organization in the chromosome, the expression of cap5 and cap8 genes is subject to similar transcriptional regulation. To date, a large number of regulators affecting cap gene transcription, some of which are non-DNA-binding factors, have been identified and/or characterized, and they include MgrA, AgrADBC, ArlRS, SaeRS, CodY, KdpDE, SigB, SpoVG, ClpC, ClpP, SbcDC, RpiRC, CcpA, Rot, CcpE,[12][13][14][15][16][17][18][19][20].Staphylococcal capsules are involved in immune evasion, but they can also mask cell surface components, such as adhesins, that are important for pathogenesis (21,22). Thus, the production of capsule must be controlled properly depending on the conditions of the environment in which S. aureus resides.…”

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confidence: 99%

RbsR Activates Capsule but Represses the rbsUDK Operon in Staphylococcus aureus

Lei

Lee

2015

J Bacteriol

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Staphylococcus aureus capsule is an important virulence factor that is regulated by a large number of regulators. Capsule genes are expressed from a major promoter upstream of the cap operon. A 10-bp inverted repeat (IR) located 13 bp upstream of the ؊35 region of the promoter was previously shown to affect capsule gene transcription. However, little is known about transcriptional activation of the cap promoter. To search for potential proteins which directly interact with the cap promoter region (Pcap), we directly analyzed the proteins interacting with the Pcap DNA fragment from shifted gel bands identified by electrophoretic mobility shift assay. One of these regulators, RbsR, was further characterized and found to positively regulate cap gene expression by specifically binding to the cap promoter region. Footprinting analyses showed that RbsR protected a DNA region encompassing the 10-bp IR. Our results further showed that rbsR was directly controlled by SigB and that RbsR was a repressor of the rbsUDK operon, involved in ribose uptake and phosphorylation. The repression of rbsUDK by RbsR could be derepressed by D-ribose. However, D-ribose did not affect RbsR activation of capsule. IMPORTANCEStaphylococcus aureus is an important human pathogen which produces a large number of virulence factors. We have been using capsule as a model virulence factor to study virulence regulation. Although many capsule regulators have been identified, the mechanism of regulation of most of these regulators is unknown. We show here that RbsR activates capsule by direct promoter binding and that SigB is required for the expression of rbsR. These results define a new pathway wherein SigB activates capsule through RbsR. Our results further demonstrate that RbsR inhibits the rbs operon involved in ribose utilization, thereby providing an example of coregulation of metabolism and virulence in S. aureus. Thus, this study further advances our understanding of staphylococcal virulence regulation. Staphylococcus aureus produces a large number of virulence factors that endow the organism with the ability to cause a wide range of diseases in humans and animals. The expression of virulence genes is controlled by an equally impressive number of regulators forming a complex regulatory network (1-3). Although the regulation of virulence genes has been the subject of extensive studies recently, our knowledge of the virulence regulatory network in S. aureus is still fragmented. To further understand virulence regulation, we have been studying the S. aureus virulence regulatory network by employing capsule as a model virulence factor (4-7). Capsule is an antiphagocytic virulence factor, and the majority of S. aureus strains produce either type 5 or type 8 capsule (8, 9). Sixteen cap genes, which are organized as a long operon, are required for the biosynthesis of either type of capsule (10). The genetic loci for the type 5 and type 8 capsules (cap5 and cap8) are allelic, with the four genes in the middle of the operon being type specific...

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Rot is a key regulator of Staphylococcus aureus biofilm formation

Cited by 70 publications

References 64 publications

Regulatory Requirements for Staphylococcus aureus Nitric Oxide Resistance

Regulatory Requirements for Staphylococcus aureus Nitric Oxide Resistance

Hyaluronan Modulation Impacts Staphylococcus aureus Biofilm Infection

RbsR Activates Capsule but Represses the rbsUDK Operon in Staphylococcus aureus

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