Enhanced purification coupled with biophysical analyses shows cross-ß structure as a core building block for Streptococcus mutans functional amyloids.
Sci Rep
; 10(1): 5138, 2020 03 20.
Article
in En
| MEDLINE
| ID: mdl-32198417
ABSTRACT
Streptococcus mutans is an etiologic agent of human dental caries that forms dental plaque biofilms containing functional amyloids. Three amyloidogenic proteins, P1, WapA, and Smu_63c were previously identified. C123 and AgA are naturally occurring amyloid-forming fragments of P1 and WapA, respectively. We determined that four amyloidophilic dyes, ThT, CDy11, BD-oligo, and MK-H4, differentiate C123, AgA, and Smu_63c amyloid from monomers, but non-specific binding to bacterial cells in the absence of amyloid precludes their utility for identifying amyloid in biofilms. Congo red-induced birefringence is a more specific indicator of amyloid formation and differentiates biofilms formed by wild-type S. mutans from a triple ΔP1/WapA/Smu_63c mutant with reduced biofilm forming capabilities. Amyloid accumulation is a late event, appearing in older S. mutans biofilms after 60 hours of growth. Amyloid derived from pure preparations of all three proteins is visualized by electron microscopy as mat-like structures. Typical amyloid fibers become evident following protease digestion to eliminate non-specific aggregates and monomers. Amyloid mats, similar in appearance to those reported in S. mutans biofilm extracellular matrices, are reconstituted by co-incubation of monomers and amyloid fibers. X-ray fiber diffraction of amyloid mats and fibers from all three proteins demonstrate patterns reflective of a cross-ß amyloid structure.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Streptococcus mutans
/
Dental Caries
/
Dental Plaque
/
Amyloid
Limits:
Humans
Language:
En
Journal:
Sci Rep
Year:
2020
Document type:
Article
Affiliation country:
Estados Unidos
Publication country:
ENGLAND
/
ESCOCIA
/
GB
/
GREAT BRITAIN
/
INGLATERRA
/
REINO UNIDO
/
SCOTLAND
/
UK
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UNITED KINGDOM