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Functional amyloids composed of phenol soluble modulins stabilize Staphylococcus aureus biofilms.

Schwartz K, Syed AK, Stephenson RE, Rickard AH, Boles BR - PLoS Pathog. (2012)

Bottom Line: Mutants unable to produce PSMs were susceptible to biofilm disassembly by matrix degrading enzymes and mechanical stress.Previous work has associated PSMs with biofilm disassembly, and we present data showing that soluble PSM peptides disperse biofilms while polymerized peptides do not.This work suggests the PSMs' aggregation into amyloid fibers modulates their biological activity and role in biofilms.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America.

ABSTRACT
Staphylococcus aureus is an opportunistic pathogen that colonizes the skin and mucosal surfaces of mammals. Persistent staphylococcal infections often involve surface-associated communities called biofilms. Here we report the discovery of a novel extracellular fibril structure that promotes S. aureus biofilm integrity. Biochemical and genetic analysis has revealed that these fibers have amyloid-like properties and consist of small peptides called phenol soluble modulins (PSMs). Mutants unable to produce PSMs were susceptible to biofilm disassembly by matrix degrading enzymes and mechanical stress. Previous work has associated PSMs with biofilm disassembly, and we present data showing that soluble PSM peptides disperse biofilms while polymerized peptides do not. This work suggests the PSMs' aggregation into amyloid fibers modulates their biological activity and role in biofilms.

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Related in: MedlinePlus

Amyloid fiber formation modulates PSM activity.(A) S. aureus wildtype biofilms were grown in microtiter plates for 24 hours then washed and exposed to increasing concentrations of soluble αPSM1 or αPSM1 fibers at concentrations of 10, 50 or 100 µg/mL for six hours. Biofilms were then washed, stained and remaining biofilm biomass was visualized (images of wells below graph) and quantitated (OD at A595). (B & C) TEM micrographs of αPSM1 samples used in the experiment demonstrate the absence (B) and presence (C) of fibers. * P<0.002 compared to control no αPSM1 treatment. We verified that αPSM1 fibers bind CR (D) and ThT (E) similar to amyloid fibers.
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ppat-1002744-g008: Amyloid fiber formation modulates PSM activity.(A) S. aureus wildtype biofilms were grown in microtiter plates for 24 hours then washed and exposed to increasing concentrations of soluble αPSM1 or αPSM1 fibers at concentrations of 10, 50 or 100 µg/mL for six hours. Biofilms were then washed, stained and remaining biofilm biomass was visualized (images of wells below graph) and quantitated (OD at A595). (B & C) TEM micrographs of αPSM1 samples used in the experiment demonstrate the absence (B) and presence (C) of fibers. * P<0.002 compared to control no αPSM1 treatment. We verified that αPSM1 fibers bind CR (D) and ThT (E) similar to amyloid fibers.

Mentions: Previous work has demonstrated that soluble PSMs assist biofilm disassembly [19], [21], [27]. Based on our findings that PSM fibers improve biofilm integrity (Fig. 1 & Fig. 7), we hypothesized that sequestration of PSMs into extracellular fibers could alter their activity. Synthetic αPSM1 peptides readily formed fibers that bind CR and ThT after 24 hours of incubation in solution (Fig. 8C, 8D, 8E). To test whether or not fibrillation alters peptide activity, we exposed 24-hour S. aureus biofilms to either freshly solublized αPSM1 peptides (Fig. 8B) or αPSM1 that had been allowed to polymerize overnight (Fig. 8C). Exposure to soluble αPSM1 significantly reduced the amount of adherent biofilm; however, exposure to αPSM1 fibers had no discernable effect on the biofilms (Fig. 8A). This finding suggests that the aggregation of PSMs into amyloid-like fibers can modulate their ability to disassemble biofilms.


Functional amyloids composed of phenol soluble modulins stabilize Staphylococcus aureus biofilms.

Schwartz K, Syed AK, Stephenson RE, Rickard AH, Boles BR - PLoS Pathog. (2012)

Amyloid fiber formation modulates PSM activity.(A) S. aureus wildtype biofilms were grown in microtiter plates for 24 hours then washed and exposed to increasing concentrations of soluble αPSM1 or αPSM1 fibers at concentrations of 10, 50 or 100 µg/mL for six hours. Biofilms were then washed, stained and remaining biofilm biomass was visualized (images of wells below graph) and quantitated (OD at A595). (B & C) TEM micrographs of αPSM1 samples used in the experiment demonstrate the absence (B) and presence (C) of fibers. * P<0.002 compared to control no αPSM1 treatment. We verified that αPSM1 fibers bind CR (D) and ThT (E) similar to amyloid fibers.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3369951&req=5

ppat-1002744-g008: Amyloid fiber formation modulates PSM activity.(A) S. aureus wildtype biofilms were grown in microtiter plates for 24 hours then washed and exposed to increasing concentrations of soluble αPSM1 or αPSM1 fibers at concentrations of 10, 50 or 100 µg/mL for six hours. Biofilms were then washed, stained and remaining biofilm biomass was visualized (images of wells below graph) and quantitated (OD at A595). (B & C) TEM micrographs of αPSM1 samples used in the experiment demonstrate the absence (B) and presence (C) of fibers. * P<0.002 compared to control no αPSM1 treatment. We verified that αPSM1 fibers bind CR (D) and ThT (E) similar to amyloid fibers.
Mentions: Previous work has demonstrated that soluble PSMs assist biofilm disassembly [19], [21], [27]. Based on our findings that PSM fibers improve biofilm integrity (Fig. 1 & Fig. 7), we hypothesized that sequestration of PSMs into extracellular fibers could alter their activity. Synthetic αPSM1 peptides readily formed fibers that bind CR and ThT after 24 hours of incubation in solution (Fig. 8C, 8D, 8E). To test whether or not fibrillation alters peptide activity, we exposed 24-hour S. aureus biofilms to either freshly solublized αPSM1 peptides (Fig. 8B) or αPSM1 that had been allowed to polymerize overnight (Fig. 8C). Exposure to soluble αPSM1 significantly reduced the amount of adherent biofilm; however, exposure to αPSM1 fibers had no discernable effect on the biofilms (Fig. 8A). This finding suggests that the aggregation of PSMs into amyloid-like fibers can modulate their ability to disassemble biofilms.

Bottom Line: Mutants unable to produce PSMs were susceptible to biofilm disassembly by matrix degrading enzymes and mechanical stress.Previous work has associated PSMs with biofilm disassembly, and we present data showing that soluble PSM peptides disperse biofilms while polymerized peptides do not.This work suggests the PSMs' aggregation into amyloid fibers modulates their biological activity and role in biofilms.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America.

ABSTRACT
Staphylococcus aureus is an opportunistic pathogen that colonizes the skin and mucosal surfaces of mammals. Persistent staphylococcal infections often involve surface-associated communities called biofilms. Here we report the discovery of a novel extracellular fibril structure that promotes S. aureus biofilm integrity. Biochemical and genetic analysis has revealed that these fibers have amyloid-like properties and consist of small peptides called phenol soluble modulins (PSMs). Mutants unable to produce PSMs were susceptible to biofilm disassembly by matrix degrading enzymes and mechanical stress. Previous work has associated PSMs with biofilm disassembly, and we present data showing that soluble PSM peptides disperse biofilms while polymerized peptides do not. This work suggests the PSMs' aggregation into amyloid fibers modulates their biological activity and role in biofilms.

Show MeSH
Related in: MedlinePlus