Abstract
Group-3 late embryogenesis abundant
(G3LEA) proteins play important roles in the acquisition
of desiccation tolerance in some anhydrobiotic
organisms such as African sleeping chironomide. From
their primary amino acid sequences, the potential
functional sites are inferred to be located at segments that
include several times repeats of 11-mer motifs, such as
AKDGTKEKAGE, characteristic of G3LEA proteins. So
far, we have investigated the structural and functional
properties of chemically synthesized 22-mer or 44-mer
peptides that include one of the consensus 11-mer motifs
identified by bioinformatics analysis for various G3LEA
proteins. Our findings to be noted are as follows. Such
LEA model peptides can reproduce the structural features
of the parent G3LEA proteins: they are disordered in
water, whereas they adopt -helical coiled coil structure
in the dry state. The dried peptides are in the glassy state
up to 100 ºC, and have the ability of reinforcing the
glassy matrix of co-existing sugar such as trehalose.
More importantly, the LEA model peptides have
protective activities on various biological molecules
against the desiccation stress. For example, they exhibit
anti-fusion effect on liposomes in the dry state by
covering the membrane surface through the interactions
between the side chains of their Lys residues and the
polar head groups of phospholipid molecules. In addition,
the LEA model peptides are capable not only of
suppressing the desiccation-induced aggregation of
proteins such as lysozyme and -casein, but also of
preserving the catalytic activities of electrostatically
different enzymes such as lactate dehydrogenase and
-D-galactosidase, whose pI values are 4.6 and 8.2,
respectively. On the basis of these results, the LEA
model peptides developed by our group are expected to
be applicable to dry preservation of a variety of
biological molecules.
