Protein HGFI from the edible mushroom Grifola frondosa is a novel 8 kDa class I hydrophobin that forms rodlets in compressed monolayers

Abstract

Hydrophobins are a group of low-molecular-mass, cysteine-rich proteins that have unusual biophysical properties. They are highly surface-active and can self-assemble at hydrophobic-hydrophilic interfaces, forming surface layers that are able to reverse the hydropathy of surfaces. Here we describe a novel hydrophobin from the edible mushroom Grifola frondosa, which was named HGFI and belongs to class I. The hydrophobin gene was identified during sequencing of random clones from a cDNA library, and the corresponding protein was isolated as a hot SDS-insoluble aggregate from the cell wall. The purified HGFI was found to have 83 amino acids. The protein sequence deduced from the cDNA sequence had 107 amino acids, from which a 24 aa signal sequence had been cleaved off in the mature protein. This signal sequence was 5 aa longer than had been predicted on the basis of signal peptide analysis of the cDNA. Rodlet mosaic structures were imaged using atomic force microscopy (AFM) on mica surfaces after drying-down HGFI solutions. Using Langmuir films we were also able to take images of both the hydrophobic and hydrophilic sides of films formed at the air-water interface. No distinct structure was observed in films compressed once, but in films compressed several times rodlet structures could be seen. Most rodlets were aligned in the same direction, indicating that formation of rodlets may be promoted during compression of the monolayer.

Heterologous expression and characterization of the hydrophobin HFBI in Pichia pastoris and evaluation of its contribution to the food industry

“…The supernatant was purified by ultrafiltration using a hollow fiber membrane module (Tianjin MOTIMO Membrane Technology Ltd., China) and then lyophilized. Further purification was accomplished using A Vydac C4 reversed-phase column (4.6 9 250 mm, GRACE, China) according to Yu's method (Yu et al 2008). The resulting elutes of the targeted protein were analyzed by 16% Tricine-SDS-PAGE and Western blotting.…”

The antioxidant properties of polypore mushroom Daedaleopsis confragosa

“…The polyporales are among the most common and easily identifiable group of wild mushrooms. They are usually inedible, because of its hardness and woody structure, except for a few special edible species [1,2]. Almost all of these mushrooms grow on wooden bases such as trees, logs and stumps.…”

A visualized fusion protein based on self-assembly hydrophobin HGFI

“…On the contrary, the membranes formed by Class II hydrophobins display soluble characteristic very well under the same conditions [6,24] . So a probable deduction is that the interaction of adsorbed Class I hydrophobins with hydrophobic-hydrophilic interfaces is more powerful than that of adsorbed Class II hydrophobins with them.…”

“…Hydrophobin HGFI was used to modify the surface of siliconized glass whose water contact angle(WCA) was changed from 86.6° to 51.9°, suggesting the wettability of glass surface reversed from hydrophobicity to hydrophilicity [6] . The most well-known hydrophobin SC3 was fixed onto the polystyrene(PS) surface, rendering the evident reduction of its surface friction coefficient compared to that of the bare PS [7] .…”