An Electrostatic Net Model for the Role of Extracellular DNA in Biofilm Formation by Staphylococcus aureus

Dengler, Vanina; Foulston, Lucy; DeFrancesco, Alicia S.; Losick, Richard

doi:10.1128/jb.00726-15

Cited by 118 publications

(135 citation statements)

References 44 publications

Supporting

Mentioning

120

Contrasting

Order By: Relevance

“…Under biofilm-inducing conditions, extracellular complementation would mask insertions that fail to contribute eDNA because these mutants would be retained in the biofilm by virtue of the eDNA released by other cells in the population. To circumvent this problem, we took advantage of a prior observation that mature biofilms release their matrix, including the eDNA component, when the cells are suspended at a neutral pH (7.5) buffer (6). We therefore grew a biofilm using a mixed inoculum representing a highly saturated transposon library and proceeded to isolate eDNA recovered by neutralization of the biofilm environment.…”

Section: Resultsmentioning

confidence: 99%

“…that the eDNA component of the biofilm matrix is released into the medium when the cells are suspended in a buffer at a higher pH (6). This method enabled us to separate eDNA in the matrix from genomic DNA (gDNA), which we extracted from cells in the biofilm.…”

Section: Significancementioning

confidence: 99%

“…Next, we asked whether the genes identified in our screen are needed for the release of eDNA during biofilm formation when the mutants are grown individually in pure culture. We constructed null mutants for nine of these genes (ΔyybS, ΔfmtA, Δ1025, ΔalsT, ΔansA, Δapt, ΔccpA, ΔxdrA, ΔgidA) in the present work, and also used a previously generated mutant (ΔsarA) (6). Additionally, a transposon insertion in an 11th gene, gdpP, was recovered by using a strategy described below.…”

Section: Mutants Of Genes Underrepresented For Transposon Insertions mentioning

confidence: 99%

“…We have shown that the major components of the biofilm matrix of HG003 are proteins and eDNA, which associate with the biofilm in a manner that depends on a drop in pH during growth in the presence of glucose (5,6). Many of these proteins are cytoplasmic in origin and are thus moonlighting in their second role as components of the biofilm matrix (5).…”

mentioning

confidence: 99%

“…These moonlighting proteins do not depend on eDNA to remain associated with cells. The eDNA, however, requires the presence of matrix proteins to adhere to the cells, serving as an electrostatic net that holds cells together in large clumps (6). eDNA is a critical component of the matrix of the HG003 staphylococcal biofilm, because DNase I treatment of biofilm cells leads to a marked reduction in clumping and a partial reduction in biofilm biomass (6).…”

mentioning

confidence: 99%

See 4 more Smart Citations

Genome-wide screen for genes involved in eDNA release during biofilm formation by Staphylococcus aureus

DeFrancesco

Masloboeva

Syed

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

101

103

View full text Add to dashboard Cite

Staphylococcus aureus is a leading cause of both nosocomial and community-acquired infection. Biofilm formation at the site of infection reduces antimicrobial susceptibility and can lead to chronic infection. During biofilm formation, a subset of cells liberate cytoplasmic proteins and DNA, which are repurposed to form the extracellular matrix that binds the remaining cells together in large clusters. Using a strain that forms robust biofilms in vitro during growth under glucose supplementation, we carried out a genome-wide screen for genes involved in the release of extracellular DNA (eDNA). A high-density transposon insertion library was grown under biofilm-inducing conditions, and the relative frequency of insertions was compared between genomic DNA (gDNA) collected from cells in the biofilm and eDNA from the matrix. Transposon insertions into genes encoding functions necessary for eDNA release were identified by reduced representation in the eDNA. On direct testing, mutants of some of these genes exhibited markedly reduced levels of eDNA and a concomitant reduction in cell clustering. Among the genes with robust mutant phenotypes were gdpP, which encodes a phosphodiesterase that degrades the second messenger cyclic-di-AMP, and xdrA, the gene for a transcription factor that, as revealed by RNA-sequencing analysis, influences the expression of multiple genes, including many involved in cell wall homeostasis. Finally, we report that growth in biofilm-inducing medium lowers cyclicdi-AMP levels and does so in a manner that depends on the gdpP phosphodiesterase gene.Staphylococcus aureus | biofilm | eDNA | cyclic-di-AMP

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Significancementioning

confidence: 99%

Section: Mutants Of Genes Underrepresented For Transposon Insertions mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Genome-wide screen for genes involved in eDNA release during biofilm formation by Staphylococcus aureus

DeFrancesco

Masloboeva

Syed

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

101

103

View full text Add to dashboard Cite

show abstract

Staphylococci evade the innate immune response by disarming neutrophils and forming biofilms

2020

View full text Add to dashboard Cite

Staphylococcus aureus and Staphylococcus epidermidis can cause many types of infections, ranging from skin infections to implant‐associated infections. The primary innate immune response against bacterial infections involves complement activation, recruitment of phagocytes (most importantly neutrophils), and subsequent killing of the pathogen. However, staphylococci are not innocent bystanders; they actively obstruct this immune attack. To do that, S. aureus secretes several immune‐evasion proteins to resist attack by the innate immune system. Furthermore, S. aureus and S. epidermidis are known for their ability to form biofilms on implanted medical devices and host tissues, which provides another important immune‐evasion mechanism. Understanding these different strategies to resist immune attack will help to develop novel therapies against staphylococcal infections.

show abstract

Dosage‐Dependent Antimicrobial Activity of DNA‐Histone Microwebs Against Staphylococcus Aureus

Yang

Shi

Ahmed

et al. 2021

Adv Materials Inter

View full text Add to dashboard Cite

Biofilms are surface-bound microbe assemblies encased in an extracellular matrix including extracellular DNA (eDNA), proteins, and polysaccharides, which allow bacteria to resist host immune clearing mechanisms. [1] One critical biofilm component is eDNA, which helps maintain biofilm structural integrity, [2] as well as counter host antimicrobial peptides [3] and antibiotic treatments. [4] Although eDNA can engage positively with pathogens, it is known to have an important role in the innate immune response, where neutrophils may be triggered to release neutrophil extracellular traps (NETs), [5,6] cobweb-structured DNA-histone complexes that capture and disarm microorganisms. [7,8] The observed antimicrobial activity of NET-based eDNA is due, at least in part, to their chelation with bacterial membrane proteins and subsequent lysis. [9] Histones, key NET components that modulate the self-assembly of DNA, also contribute to overall antimicrobial activity by destabilizing bacterial cell walls and chromosome organization. [10,11] It is also reported that histone inhibits biofilm formation in a dosage-dependent manner. [12] Previous studies have indicated that the antimicrobial activity of DNA or histone largely depends on their surface charges, and blockage of the surface charge results in declined antimicrobial activity. [9,11] Staphylococcus aureus is an opportunistic pathogen that can cause persistent biofilm infections in soft tissues and bones. [13] Planktonic S. aureus induces neutrophils to produce NETs that can effectively trap and suppress the bacteria. [7] On the other hand, S. aureus biofilms can thwart the antimicrobial functions of NETs by secreting nucleases to degrade the eDNA in NETs; [5,14,15] they also utilize fibronectin-binding protein B (FnBPB) and proteases to neutralize histone-mediated killing. [10,16] Producing DNA-degrading nucleases that protect them from NETs within hours of surface attachment, [5] S. aureus biofilms actively induce neutrophil NETosis to protect themselves from other granulocytic killing mechanisms. [17] In contrast to the many studies that study how biofilms affect neutrophils, NETosis, and NETs, there is no systematic analysis of how different types of NETs may impact planktonic S. aureus response in forming biofilms. This may be important because NET composition including protein content and DNA sources Neutrophil extracellular traps (NETs) are antimicrobial cobweb-structured materials produced by immune cells for clearance of pathogens in the body, but are paradoxically associated with biofilm formation and exacerbated lung infections. To provide a better materials perspective on the pleiotropic roles played by NETs at diverse compositions/concentrations, a NETs-like material (called "microwebs", abbreviated as μwebs) is synthesized for decoding the antimicrobial activity of NETs against Staphylococcus aureus in infection-relevant conditions. It is shown that μwebs composed of low-to-intermediate concentrations of DNA-histone complexes successfully trap and inhibit S...

show abstract

An Electrostatic Net Model for the Role of Extracellular DNA in Biofilm Formation by Staphylococcus aureus

Cited by 118 publications

References 44 publications

Genome-wide screen for genes involved in eDNA release during biofilm formation by Staphylococcus aureus

Genome-wide screen for genes involved in eDNA release during biofilm formation by Staphylococcus aureus

Staphylococci evade the innate immune response by disarming neutrophils and forming biofilms

Dosage‐Dependent Antimicrobial Activity of DNA‐Histone Microwebs Against Staphylococcus Aureus

Contact Info

Product

Resources

About