The Cys3-Cys4 loop of the hydrophobin EAS is not required for rodlet formation and surface activity

Kwan, Ann H., Macindoe, Ingrid, Vukasin, Paul V., Morris, Vanessa K., Kass, Itamar, Gupte, Rima, Mark, Alan E., Templeton, Matthew D., Mackay, Joel P. and Sunde, Margaret (2008) The Cys3-Cys4 loop of the hydrophobin EAS is not required for rodlet formation and surface activity. Journal of Molecular Biology, 382 3: 708-720. doi:10.1016/j.jmb.2008.07.034


Author Kwan, Ann H.
Macindoe, Ingrid
Vukasin, Paul V.
Morris, Vanessa K.
Kass, Itamar
Gupte, Rima
Mark, Alan E.
Templeton, Matthew D.
Mackay, Joel P.
Sunde, Margaret
Title The Cys3-Cys4 loop of the hydrophobin EAS is not required for rodlet formation and surface activity
Journal name Journal of Molecular Biology   Check publisher's open access policy
ISSN 0022-2836
Publication date 2008-07-22
Sub-type Article (original research)
DOI 10.1016/j.jmb.2008.07.034
Volume 382
Issue 3
Start page 708
End page 720
Total pages 13
Place of publication United Kingdom
Publisher Academic Press
Collection year 2009
Language eng
Subject C1
060112 Structural Biology (incl. Macromolecular Modelling)
Abstract Class I hydrophobins are fungal proteins that self-assemble into robust amphipathic rodlet monolayers on the surface of aerial structures such as spores and fruiting bodies. These layers share many structural characteristics with amyloid fibrils and belong to the growing family of functional amyloid-like materials produced by microorganisms. Although the three-dimensional structure of the soluble monomeric form of a class I hydrophobin has been determined, little is known about the molecular structure of the rodlets or their assembly mechanism. Several models have been proposed, some of which suggest that the Cys3–Cys4 loop has a critical role in the initiation of assembly or in the polymeric structure. In order to provide insight into the relationship between hydrophobin sequence and rodlet assembly, we investigated the role of the Cys3–Cys4 loop in EAS, a class I hydrophobin from Neurospora crassa. Remarkably, deletion of up to 15 residues from this 25-residue loop does not impair rodlet formation or reduce the surface activity of the protein, and the physicochemical properties of rodlets formed by this mutant are indistinguishable from those of its full-length counterpart. In addition, the core structure of the truncation mutant is essentially unchanged. Molecular dynamics simulations carried out on the full-length protein and this truncation mutant binding to an air–water interface show that, although it is hydrophobic, the loop does not play a role in positioning the protein at the surface. These results demonstrate that the Cys3–Cys4 loop does not have an integral role in the formation or structure of the rodlets and that the major determinant of the unique properties of these proteins is the amphipathic core structure, which is likely to be preserved in all hydrophobins despite the high degree of sequence variation across the family.
Keyword hydrophobin
EAS
rodlets
assembly
amyloid
Q-Index Code C1
Q-Index Status Confirmed Code

 
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Created: Fri, 27 Mar 2009, 22:28:34 EST by Glenda Chown on behalf of School of Chemistry & Molecular Biosciences