The two published structures of class II hydrophobins are
very similar to each other, reflecting the high level of sequence
homology between HFBI and HFBII and possibly also the high
degree of sequence conservation within this class of hydrophobins.
In contrast, the structures of the class I hydrophobins
EAS and DewA are more dissimilar and reflect the large differences
in sequence between these two proteins. They also contain
noticeably more flexible regions than do the class II
hydrophobins, which is possibly a result of their longer sequences.
Determination of the structure of another class II hydrophobin,
perhaps in solution rather than by crystallography,
could shed light on the structural conservation within that
class and the significance of the observation of structural flexibility
in the presence of detergent.32,33 All of the hydrophobin
structures have a relatively large exposed surface hydrophobicity
accounting for more than 60% of the total accessible surface
area, which presumably underlies their surface activity and
ability to form amphipathic monolayers (Figure 5B).