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Characterization of a Basidiomycota hydrophobin reveals the structural basis for a high-similarity Class I subdivision

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ABSTRACT

Class I hydrophobins are functional amyloids secreted by fungi. They self-assemble into organized films at interfaces producing structures that include cellular adhesion points and hydrophobic coatings. Here, we present the first structure and solution properties of a unique Class I protein sequence of Basidiomycota origin: the Schizophyllum commune hydrophobin SC16 (hyd1). While the core β-barrel structure and disulphide bridging characteristic of the hydrophobin family are conserved, its surface properties and secondary structure elements are reminiscent of both Class I and II hydrophobins. Sequence analyses of hydrophobins from 215 fungal species suggest this structure is largely applicable to a high-identity Basidiomycota Class I subdivision (IB). To validate this prediction, structural analysis of a comparatively distinct Class IB sequence from a different fungal order, namely the Phanerochaete carnosa PcaHyd1, indicates secondary structure properties similar to that of SC16. Together, these results form an experimental basis for a high-identity Class I subdivision and contribute to our understanding of functional amyloid formation.

No MeSH data available.


SC16 structural features are reminiscent of Class II hydrophobins.(A) Schematics of the secondary structure elements of SC16, the Class I hydrophobins (EAS, DewA and MPG1), and the Class II hydrophobins (HFBI, HFBII, and NC2). Both β-sheets (1-4) and intervening loops (L1-L3) are indicated. Superposition of the β-sheet core of SC16 (blue) with the Class I hydrophobins EAS (B; red), DewA (C; green), and MPG1 (D; yellow) and (E) the Class II hydrophobins HFBI, HFBII, and NC2 (purple, teal, and grey, respectively).
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f3: SC16 structural features are reminiscent of Class II hydrophobins.(A) Schematics of the secondary structure elements of SC16, the Class I hydrophobins (EAS, DewA and MPG1), and the Class II hydrophobins (HFBI, HFBII, and NC2). Both β-sheets (1-4) and intervening loops (L1-L3) are indicated. Superposition of the β-sheet core of SC16 (blue) with the Class I hydrophobins EAS (B; red), DewA (C; green), and MPG1 (D; yellow) and (E) the Class II hydrophobins HFBI, HFBII, and NC2 (purple, teal, and grey, respectively).

Mentions: Of the structural features displayed by SC16, some were consistent with those previously observed in hydrophobins while others were unique. SC16 maintained the key features of the hydrophobin fold: a central four-strand β-sheet and four disulphide bonds (Fig. 2)81920212223. Notably, in solution its sheet adopted a compact β-barrel structure more similar to the core structures of the Class II hydrophobins HFBI and HFBII (backbone atom root mean squared deviation of 3.0 Å and 2.2 Å, respectively; Fig. 3E) than to those of other Class I and II hydrophobins. These, in contrast to SC16, were observed as either open or irregular barrel structures (Fig. 3A–D).


Characterization of a Basidiomycota hydrophobin reveals the structural basis for a high-similarity Class I subdivision
SC16 structural features are reminiscent of Class II hydrophobins.(A) Schematics of the secondary structure elements of SC16, the Class I hydrophobins (EAS, DewA and MPG1), and the Class II hydrophobins (HFBI, HFBII, and NC2). Both β-sheets (1-4) and intervening loops (L1-L3) are indicated. Superposition of the β-sheet core of SC16 (blue) with the Class I hydrophobins EAS (B; red), DewA (C; green), and MPG1 (D; yellow) and (E) the Class II hydrophobins HFBI, HFBII, and NC2 (purple, teal, and grey, respectively).
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5385502&req=5

f3: SC16 structural features are reminiscent of Class II hydrophobins.(A) Schematics of the secondary structure elements of SC16, the Class I hydrophobins (EAS, DewA and MPG1), and the Class II hydrophobins (HFBI, HFBII, and NC2). Both β-sheets (1-4) and intervening loops (L1-L3) are indicated. Superposition of the β-sheet core of SC16 (blue) with the Class I hydrophobins EAS (B; red), DewA (C; green), and MPG1 (D; yellow) and (E) the Class II hydrophobins HFBI, HFBII, and NC2 (purple, teal, and grey, respectively).
Mentions: Of the structural features displayed by SC16, some were consistent with those previously observed in hydrophobins while others were unique. SC16 maintained the key features of the hydrophobin fold: a central four-strand β-sheet and four disulphide bonds (Fig. 2)81920212223. Notably, in solution its sheet adopted a compact β-barrel structure more similar to the core structures of the Class II hydrophobins HFBI and HFBII (backbone atom root mean squared deviation of 3.0 Å and 2.2 Å, respectively; Fig. 3E) than to those of other Class I and II hydrophobins. These, in contrast to SC16, were observed as either open or irregular barrel structures (Fig. 3A–D).

View Article: PubMed Central - PubMed

ABSTRACT

Class I hydrophobins are functional amyloids secreted by fungi. They self-assemble into organized films at interfaces producing structures that include cellular adhesion points and hydrophobic coatings. Here, we present the first structure and solution properties of a unique Class I protein sequence of Basidiomycota origin: the Schizophyllum commune hydrophobin SC16 (hyd1). While the core β-barrel structure and disulphide bridging characteristic of the hydrophobin family are conserved, its surface properties and secondary structure elements are reminiscent of both Class I and II hydrophobins. Sequence analyses of hydrophobins from 215 fungal species suggest this structure is largely applicable to a high-identity Basidiomycota Class I subdivision (IB). To validate this prediction, structural analysis of a comparatively distinct Class IB sequence from a different fungal order, namely the Phanerochaete carnosa PcaHyd1, indicates secondary structure properties similar to that of SC16. Together, these results form an experimental basis for a high-identity Class I subdivision and contribute to our understanding of functional amyloid formation.

No MeSH data available.