Adsorption kinetics and self assembled structures of Aspergillus oryzae hydrophobin RolA on chemically modified solid surfaces.

Y. Terauchia, M. Nagayamaa, T. Tanakaa, H. Tanabea, T. Aritab, H. Higuchib, F. Hasegawac and K. Abea,c

Author address: 

aDept. Microbial biotechnology, Grad. Sch. Agricult. Sci., Tohoku Univ., Sendai, Miyagi, JP bIMRAM, Tohoku University c NICHe, Tohoku University


Hydrophobins are amphipathic proteins that are ubiquitous among filamentous fungi, and required for the
formation of fungal aerial structures (1). Hydrophobins also play an important role in the infection of
pathogenic fungi because hydrophobins are not recognized by pattern recognition receptors of animals
and plants (2, 3). The industrial fungus Aspergillus oryzae produces a hydrophobin RolA (4). RolA
attaches and self-assembles on solid surfaces such as polyesters, and recruits an esterase CutL1, which
results in stimulation of the hydrolysis of polyester by CutL1 (4). RolA also evades from recognition by
mouse immune system (unpublished results). Because of these properties, RolA is expected to be
applicable to industrial and medical fields. Therefore, kinetic properties and self-assembled properties of
RolA-adsorption on solid surfaces are important. To investigate kinetic properties and self-assembled
structures of RolA on solid surfaces, we constructed self-assembled monolayers (SAM) of 1-undcanethiol
(hydrophobic), 11-amino-1-undecanethiol (cationic), and 10-carboxy-1-undecanethiol (anionic) on the
electrodes of a Quartz Crystal Microbalance (QCM). We analyzed kinetics of RolA-adsorption on SAMelectrodes
at various pH, and then observed self assembled structures of RolA by an AFM. Affinities
between RolA and all SAM-electrodes were highest at pH 4 and lowest at pH 10. The forms of selfassembled
structure of RolA depended on the pH values, amounts of adsorbed RolA, and functional
groups of SAMs. Rod-like structures of self-assembled RolA were observed on all SAM-electrodes at pH
4. In addition, surface tensions of SAM-electrodes were modified by RolA adsorption. Overall, these
results suggest that hydrophobic and electrostatic interactions between RolA molecules adsorbed on
SAM-electrodes and soluble RolA molecules in water-phase depend on pH values and mainly contributed
to the kinetics of RolA adsorption and self-assembly of RolA molecules on solid surfaces.
1) Wösten H. A., Annu Rev Microbiol. 55: 625 (2001)
2) Aimanianda V. et al., Nature. 460:1117 (2009)
3) Martellini F. et al., Mol Biotechnol. 55: 27 (2013)
4) Takahashi T. et al., Mol Microbiol. 96: 14 (2015)


abstract No: 


Full conference title: 

The Fourteenth International Aspergillus Meeting, Asilomar Conference Center, Pacific Grove, CA, USA
    • Asperfest 14 (2017)