Enhanced purification coupled with biophysical analyses shows cross-β structure as a core building block for Streptococcus mutans functional amyloids

Autor: Surabhi Mishra, Momin Haider, Ana L. Barrán-Berdón, L. Jeannine Brady, Stephen J. Hagen, Amy Kendall, Joanna R. Long, Elena G. Yarmola, Gerald Stubbs, Joyce C. Morales-Aparicio, Gregory Ottenberg, Sebastian Ocampo
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Scientific Reports, Vol 10, Iss 1, Pp 1-11 (2020)
Scientific Reports
ISSN: 2045-2322
Popis: 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-β amyloid structure.
Databáze: OpenAIRE
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