TY - JOUR
T1 - Fibrilar polymorphism of the bacterial extracellular matrix protein tasa
AU - Ghrayeb, Mnar
AU - Hayet, Shahar
AU - Lester-Zer, Neta
AU - Levi-Kalisman, Yael
AU - Chai, Liraz
N1 - Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2021/3
Y1 - 2021/3
N2 - Functional amyloid proteins often appear as fibers in extracellular matrices of microbial soft colonies. In contrast to disease-related amyloid structures, they serve a functional goal that benefits the organism that secretes them, which is the reason for the title “functional”. Biofilms are a specific example of a microbial community in which functional amyloid fibers play a role. Functional amyloid proteins contribute to the mechanical stability of biofilms and mediate the adhesion of the cells to themselves as well as to surfaces. Recently, it has been shown that functional amyloid proteins also play a regulatory role in biofilm development. TasA is the major proteinaceous fibrilar component of the extracellular matrix of biofilms made of the soil bacterium and Gram-positive Bacillus subtilis. We have previously shown, as later corroborated by others, that in acidic solutions, TasA forms compact aggregates that are composed of tangled fibers. Here, we show that in a neutral pH and above a certain TasA concentration, the fibers of TasA are elongated and straight and that they bundle up in highly concentrated salt solutions. TasA fibers resemble the canonic amyloid morphology; however, these fibers also bear an interesting nm-scale periodicity along the fiber axis. At the molecular level, TasA fibers contain a twisted β-sheet structure, as indicated by circular di-chroism measurements. Our study shows that the morphology of TasA fibers depends on the environmental conditions. Different fibrilar morphologies may be related with different functional roles in biofilms, ranging from granting biofilms with a mechanical support to acting as antibiotic agents.
AB - Functional amyloid proteins often appear as fibers in extracellular matrices of microbial soft colonies. In contrast to disease-related amyloid structures, they serve a functional goal that benefits the organism that secretes them, which is the reason for the title “functional”. Biofilms are a specific example of a microbial community in which functional amyloid fibers play a role. Functional amyloid proteins contribute to the mechanical stability of biofilms and mediate the adhesion of the cells to themselves as well as to surfaces. Recently, it has been shown that functional amyloid proteins also play a regulatory role in biofilm development. TasA is the major proteinaceous fibrilar component of the extracellular matrix of biofilms made of the soil bacterium and Gram-positive Bacillus subtilis. We have previously shown, as later corroborated by others, that in acidic solutions, TasA forms compact aggregates that are composed of tangled fibers. Here, we show that in a neutral pH and above a certain TasA concentration, the fibers of TasA are elongated and straight and that they bundle up in highly concentrated salt solutions. TasA fibers resemble the canonic amyloid morphology; however, these fibers also bear an interesting nm-scale periodicity along the fiber axis. At the molecular level, TasA fibers contain a twisted β-sheet structure, as indicated by circular di-chroism measurements. Our study shows that the morphology of TasA fibers depends on the environmental conditions. Different fibrilar morphologies may be related with different functional roles in biofilms, ranging from granting biofilms with a mechanical support to acting as antibiotic agents.
KW - Bacillus subtilis
KW - Extracellular matrix
KW - Functional amyloid
KW - Protein aggregation
KW - TasA
UR - http://www.scopus.com/inward/record.url?scp=85102013477&partnerID=8YFLogxK
U2 - 10.3390/microorganisms9030529
DO - 10.3390/microorganisms9030529
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AN - SCOPUS:85102013477
SN - 2076-2607
VL - 9
SP - 1
EP - 12
JO - Microorganisms
JF - Microorganisms
IS - 3
M1 - 529
ER -