INVESTIGADORES
ITUARTE Santiago
congresos y reuniones científicas
Título:
Structure-function relationships of ovorubin, a protease inhibitor from the eggs of Pomacea canaliculata
Autor/es:
DREÓN, MS; ITUARTE, S; CEOLÍN, M; HERAS, H
Lugar:
Buzios, Brasil
Reunión:
Congreso; VII Iberoamerican Congress of Biological Physics; 2009
Institución organizadora:
Sociedad Argentina de Biofísica
Resumen:
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Ovorubin (OR) is
the major egg protein from the apple snail (Pomacea
canaliculata) perivitellin fluid (PVF). It plays essential roles in embryo
development, including transport and protection of carotenoids, protease
inhibition, photoprotection, storage, and nourishment.
It is a lipo-glyco-carotenoprotein complex with an
apparent molecular mass of 300 kDa composed of three subunits of ca. 28, 32,
and 35 kDa. OR has a pinkish-red colour, due to the cofactor astaxanthin
(3,3´-hydroxy-β-β-carotene-4,4´-dione), a potent antioxidant, that protects the
embryos from photoxidative damage. In this work, we focussed
on the primary structural features of OR and analyzed their functional
implications.
The 28 KDa subunit of OR was cloned based
on its N-terminal sequence, BLAST analysis of its nucleotide sequence showed a
high degree of homology to puroindoline a plant antimicrobial peptide,
nevertheless no functional correlations could be established. On the other hand,
using the partial amino acid
sequence of chemically-deglycosilated OR obtained
by mass spectrometry showed a high degree of homology with a member of
the Kunitz inhibitor family. This Kunitz motif, provided
the first evidence of the nature of the inhibitor. Studies of the physical
interactions between trypsin and OR by cross-linking and Western blot assays as
well as small angle X-ray scattering (SAXS) gave further evidence of the
interaction of OR with serine proteases. Moreover, SAXS results showed a 1:1
complex between OR and trypsin.
Finally,
studies of simulated gastrointestinal digestion showed that OR retained its
trypsin inhibition capacity, clearly indicating the physiological implication
of these findings.
This
led us to suggest a novel role for OR during P. canaliculata embryogenesis as an antinutritive protein rather
than simply preventing bacterial invasions as was previously suggested.
