Processing and accumulation of low molecular Weight glutenin subunits in wheat endosperm
Author(s)
Egidi, Eleonora
Date Issued
April 20, 2012
Type
Doctoral Thesis
Abstract
Among the various classes of LMW-GS, the most abundant are LMW-m and LMW-s, so called according to
the first amino acid of mature sequence (Met and Ser respectively). We have hypothesized that the presence
of the Asn residue in position 23 of LMW-s types determines a different maturation process, that might
generate the cleavage of the peptide MEN by an Asparaginyl endoprotease. For this reason, the coding genes
for these two protein types were mutated in position 23 in order to have Thr instead of Asn and viceversa.
The mutated gene versions have been used to transform plants of durum wheat. The wild-type LMW-m type
was used as control.
Our hypotheses was confirmed in both cases. In regard to the mutated LMW-m type, MS analysis and Nterminal
sequencing demonstrated that the mature peptide began with SCISGLERP-, like LMW-s type.
Similarly, for the mutated LMW-s type, the N-terminal mature polypeptide was METSHIP, as for LMW-m
type.
Moreover, we set up a strategy that allows to study trafficking of LMW-GS and of other wheat storage
proteins.No clear conclusion at this regard has in fact been reached yet. To work out this problem, constructs
containing markers for cellular compartments (Vacuole, Golgi and ER) were used to transform wheat plants
in order to monitor their intra-cellular trafficking, to backcross with other transgenic plants transformed with
LMW-GS containing different tags, in order to eventually establish the precise route of deposition.
Additional information
Dottorato di ricerca in Biotecnologie vegetali
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