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Antioxidant systems in seeds: Functions of 1-Cys Peroxiredoxin and Ascorbate during embryogenesis and germination.Posted by: University of Sao Paulo
Posted date: May-24-2019
Location: Sao Paulo, SP
PD Fellowship in Redox Processes and Seed Biology
Title: Antioxidant systems in seeds: Functions of 1-Cys Peroxiredoxin and Ascorbate during embryogenesis and germination.
Number of positions: 1
Principal investigator: Luis E. S. Netto
Unit/Instituition: Instituto de Biociências -USP
Deadline for submissions: 06-13-2019
Address: Rua do Matão, 277
Departamento de Genética e Biologia
E-mail for proposal submission: nettolesib.usp.br
ABSTRACT OF THE PROPOSAL
Our research group investigates the mechanisms related to Cys-based peroxidases, such as peroxiredoxin (Prx) enzymes. We have shown that sulfenic acids (R-Cys-SOH) in enzymes of the 1-Cys Prx class can be reduced by ascorbate (vitamin C) (Monteiro et al., 2007 Proc. Natl. Acad. Sci USA), challenging the paradigm that 1-Cys Prx are specifically reduced by thiols (RSH). Thus sulfenic acid / ascorbate represents a new redox pair, whose biological relevance still needs to be assessed.
Our current challenge is to demonstrate that ascorbate can compete with other cellular reducing systems (i.e. Trx or Grx / GSH) for sulfenic acid reduction. The concentrations of these reductants in the different cellular compartments is one of the factors that can determine which system will prevail.
Plants present very high concentrations of ascorbate (3-30 mM) in several cell compartments (Zechmann et al., 2011, Zechmann 2014). On the other hand, 1-Cys Prx of plants is preferentially expressed in embryonic tissues, mainly in nuclei of seed cells and in some cases diffused in the cytoplasm (Stacy et al., 1996, 1999). Other reductive systems in addition to ascorbate, such as Thioredoxin (Trx) and Trx Reductase (TrxR) are co-localized with PER1 during seed development, including in nuclei of germinating seeds under stress (Pulido et al., 2009).
Therefore, understanding the biological significance of 1-Cys Prx reductants requires an integrated analysis, involving determination of kinetic parameters (such as kcat and Km); the distribution of the possible reductants during the life cycle of the seeds; in addition to phenotypes associated with genetic mutants. The antioxidant systems of seeds of two plants: Arabidopsis thaliana (a model organism) and Araucaria angustifolia (Brazilian pine) will be analyzed, with the collaboration of research groups led by Dr. Marie-Anne Van Sluys and Eny I.S. Floh from Department of Botany - Institute of Biosciences - USP.
The position is opened to a young scientist with a doctorate in Biochemistry, Chemistry, Biology or related areas, with experience in molecular biology techniques, including expression and purification of proteins. Previous experience in techniques related to genetic manipulations of plants, embryogenesis and seed development is desirable, but not required.
The candidate must have obtained a PhD degree for a maximum of seven years and have a proven record of published papers, demonstrating capacity to act in the development of the project. Candidates must have fluency in English and dedicate themselves fully and exclusively to the project activities.
The position is open to Brazilians and foreigners. The selected candidate will receive FAPESP Post-Doctoral Fellowship in the amount of R$ 7,373.10 per month and Technical Reserve equivalent to 15% of the annual value of the scholarship to meet unforeseen expenses directly related to the research activity.
Candidates should send the following documents to nettolesib.usp.br until 06/13/2019:
a) A letter of interest;
b) Curriculum vitae including a list of publications;
c) Contact information (e-mail, telephone) of two professionals who can provide letters of recommendation.
More information on the rules of FAPESP governing the operation of postdoctoral fellowships is available at www.fapesp.br/bolsas/pd.