INVESTIGADORES
ARAN Martin
congresos y reuniones científicas
Título:
Rapeseed (Brassica napus) 2-Cys peroxiredoxin: sequencing of native and recombinant forms and post-translational modifications
Autor/es:
CAPORALETTI, D. E.; ARAN, M.; GIROTTI, M.R.; LLERA, A.S.; WOLOSIUK, R.A.
Lugar:
Pilar, Buenos Aires, Argentina
Reunión:
Congreso; 1st ANNUAL IBEROAMERICAN PROTEOMICS CONGRESS; 2007
Institución organizadora:
Latinamerican Human Proteome Organization
Resumen:
Rapeseed (Brassica napus) exhibits
a restricted number of entries in databases because the complex tetraploid
genome with multiple alleles for each locus makes usually difficult the
characterization of DNA. Moreover, low-frequency post-translational
modifications of proteins are not included in databases. In this context,
tandem mass spectrometry constitutes a useful tool for the identification of
not only isolated proteins, either native or recombinant, but also the position
and composition of particular modifications. 2-Cys peroxiredoxin (2-Cys Prx) is
a large group of proteins implicated in cell differentiation, apoptosis and
photosynthesis. In this work, we describe the characterization of 2-Cys Prx by
Edman sequencing, Western blot and biochemical analysis. The native form
isolated from rapeseed leaves had minor amino acids differences relative to the
recombinant protein prepared from the cDNA, due to existence of allelic
isoforms. Matching experimental data on MS/MS with the theoretical
fragmentation of the modified peptides, we found that 2-Cys Prx could be
glutathionylated in one or both conserved cysteines, i.e., Cys53 and Cys175.
More interestingly, upon successive reduction, oxidation and incubation with
ATP and Mg2+, 2-Cys Prx became phosphorylated. Significantly, the overoxidized
forms of Cys175 were phosphorylated while Cys53, the site for sulfenic and
sufinic acid formation in mammal counterpart, remains unchanged. Hence, redox
(i.e. glutathionylation) and non-redox (phosphorylation) mechanisms converge to
conserved cysteine residues for the modulation of 2-Cys Prx functions.