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|Title: ||Caracterização da subtilisina relacionada com a degradação da ribulose bifosfato carboxilase de plantas|
|Other Titles: ||Characterization of the subtilisin correlated with rubisco proteolysis|
|Authors: ||Albuquerque, Joana Arroz Correia|
|Advisor: ||Ferreira, Ricardo Manuel Seixas Boavida|
|Issue Date: ||2009|
|Abstract: ||A subtilisin was identified, characterized and isolated from wheat leaves. In
vitro, it has the ability to degrade ribulose bisphosphate carboxylase (EC18.104.22.168;
rubisco), showing enhanced proteolytic activity towards the oxidized form of the
enzyme. During nitrogen starvation, the presence of the active form is confirmed
by detection of its autocatalytic products, which are correlated with rubisco
degradation. Rubisco proteolysis is detected in both the basal and the tip
segments of the stressed wheat leaf blade, which indicates independence from
senescence progression. This subtilisin is located in the vicinity of chloroplasts,
probably inside vesicles.
Plant subtilisins are abundant proteases that exhibit broad substrate
specificity. However, they may be induced in particular developmental stages,
where they perform specific tasks.
Stress conditions or senescence can lead to the formation of numerous
vesicles-containing proteases. Analysis of Arabidopsis thaliana transcriptome
reveals that the subtilisin under study is preferentially expressed in leaves, and its
expression is enhanced during senescence. The cysteine protease RD21A
correlates with this subtilisin, both at transcriptional level and cellular localization,
suggesting that both proteases participate in rubisco degradation.
The results suggest that the degradation of rubisco may occur outside the
chloroplasts in the senescence associated vesicles.|
|Description: ||Doutoramento em Engenharia Agronómica - Instituto Superior de Agronomia|
|Appears in Collections:||BISA - Teses de Doutoramento / Doctoral Thesis|
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