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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

An αβPSM mutant forms biofilms susceptible to disassembly by matrix degrading enzymes and mechanical stress.Confocal micrographs of Δαβpsm mutant (A) (strain BB2388) versus complemented mutant expressing α and βpsm operons in trans (B) (strain BB2408) flow cell biofilms grown for 30 hours prior to proteinase K, dispersin B, and DNaseI exposure (at 0.2 µg/mL each). Images are representative of three separate experiments and each side of a grid square represents 20 µm. (C) Analysis of biofilm development at the air-liquid interface of test tube cultures in PNG media after vortexing. Graph shows quantification of biofilm biomass (OD A595) and images below show stained test tube biofilms. * P<0.005 compared to wildtype.
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ppat-1002744-g007: An αβPSM mutant forms biofilms susceptible to disassembly by matrix degrading enzymes and mechanical stress.Confocal micrographs of Δαβpsm mutant (A) (strain BB2388) versus complemented mutant expressing α and βpsm operons in trans (B) (strain BB2408) flow cell biofilms grown for 30 hours prior to proteinase K, dispersin B, and DNaseI exposure (at 0.2 µg/mL each). Images are representative of three separate experiments and each side of a grid square represents 20 µm. (C) Analysis of biofilm development at the air-liquid interface of test tube cultures in PNG media after vortexing. Graph shows quantification of biofilm biomass (OD A595) and images below show stained test tube biofilms. * P<0.005 compared to wildtype.

Mentions: Because biofilms grown in PNG media resist disassembly by matrix-degrading enzymes and surfactants (Fig. 1), we challenged Δαβpsm mutant biofilms grown under the same conditions. In contrast to its isogenic parent strain, an Δαβpsm mutant biofilm readily disassembled after exposure to proteinase K, DNaseI, and dispersin B (Fig. 7A). Complementation of the αβPSM mutant in trans restored the resistant biofilm phenotype (Fig. 7B). We also examined the effects of mechanical stress (vortexing) on biofilms attached at the air-liquid interface of glass culture tubes. An Δαβpsm mutant biofilm readily disassembled with exposure to mechanical stress, while biofilms of the isogenic parent and complemented strains both remained intact (Fig. 7C). Taken together these data do suggest that PSM fibers enhance biofilm integrity.


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

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

An αβPSM mutant forms biofilms susceptible to disassembly by matrix degrading enzymes and mechanical stress.Confocal micrographs of Δαβpsm mutant (A) (strain BB2388) versus complemented mutant expressing α and βpsm operons in trans (B) (strain BB2408) flow cell biofilms grown for 30 hours prior to proteinase K, dispersin B, and DNaseI exposure (at 0.2 µg/mL each). Images are representative of three separate experiments and each side of a grid square represents 20 µm. (C) Analysis of biofilm development at the air-liquid interface of test tube cultures in PNG media after vortexing. Graph shows quantification of biofilm biomass (OD A595) and images below show stained test tube biofilms. * P<0.005 compared to wildtype.
© Copyright Policy
Related In: Results  -  Collection

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

ppat-1002744-g007: An αβPSM mutant forms biofilms susceptible to disassembly by matrix degrading enzymes and mechanical stress.Confocal micrographs of Δαβpsm mutant (A) (strain BB2388) versus complemented mutant expressing α and βpsm operons in trans (B) (strain BB2408) flow cell biofilms grown for 30 hours prior to proteinase K, dispersin B, and DNaseI exposure (at 0.2 µg/mL each). Images are representative of three separate experiments and each side of a grid square represents 20 µm. (C) Analysis of biofilm development at the air-liquid interface of test tube cultures in PNG media after vortexing. Graph shows quantification of biofilm biomass (OD A595) and images below show stained test tube biofilms. * P<0.005 compared to wildtype.
Mentions: Because biofilms grown in PNG media resist disassembly by matrix-degrading enzymes and surfactants (Fig. 1), we challenged Δαβpsm mutant biofilms grown under the same conditions. In contrast to its isogenic parent strain, an Δαβpsm mutant biofilm readily disassembled after exposure to proteinase K, DNaseI, and dispersin B (Fig. 7A). Complementation of the αβPSM mutant in trans restored the resistant biofilm phenotype (Fig. 7B). We also examined the effects of mechanical stress (vortexing) on biofilms attached at the air-liquid interface of glass culture tubes. An Δαβpsm mutant biofilm readily disassembled with exposure to mechanical stress, while biofilms of the isogenic parent and complemented strains both remained intact (Fig. 7C). Taken together these data do suggest that PSM fibers enhance biofilm integrity.

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