INVESTIGADORES
MUSCHIETTI jorge Prometeo
congresos y reuniones científicas
Título:
LePRK2 signal transduction in pollination: hyperphosphorylation and signaling by an unusual style peptide.
Autor/es:
MUSCHIETTI, JORGE; WENGIER, DIEGO; SALEM, TAMARA; MAZZELLA, AGUSTINA; BARBERINI, MARIA LAURA; TANG, WEI-HUA; MCCORMICK, SHEILA
Lugar:
Brasilia, Brasil.
Reunión:
Conferencia; XX International Congress on Sexual Plant Reproduction.; 2008
Institución organizadora:
International Society on Sexual Plant Reproduction
Resumen:
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Jorge P. Muschietti - "LePRK2 signal
transduction in pollination: hyperphosphorylation and signaling by an unusual
style peptide"
Muschietti, Jorge1; Wengier, Diego1; Salem, Tamara1; Mazzella, Agustina1; Barberini,
María Laura1;
Tang, Weihua3 and McCormick, Sheila2.
1,
INGEBI-CONICET-University of Buenos Aires, 2490 Vuelta de Obligado, Buenos
Aires, 1428, Argentina. 2, PGEC,
USDA/ARS-UC-Berkeley, 800 Buchanan St., Albany, CA 94710, USA. 3, SIBS-UC (Berkeley) Center of
Molecular Life Sciences, Shanghai Institutes for Biological Sciences, Chinese
Academy of Sciences, 300 Fenglin Road, Shanghai 200032, P.R. China.
e-mail: prometeo@dna.uba.ar
In compatible pollination, after pollen
grains germinate on the stigma, pollen tubes traverse the style on their way to
the ovules. During that journey, pollen tube receptors might perceive style
signals, thereby triggering cytoplasmic events required for tip growth. We
characterized two pollen-specific receptor-like kinases, LePRK1 and LePRK2,
from tomato mature pollen. Their immunolocalization pattern and the specific
LePRK2-dephosphorylation by style extract suggested that at
least LePRK2 transduces style signals (Muschietti et al., The Plant Cell 1998, 319-330). We showed in pollen, both
LePRK1 and LePRK2 are found in a high molecular weight complex that is
dissociated when pollen is germinated in
vitro in the presence of style extracts. In contrast to the typical manner
of receptor kinase activation, we propose this style component transduces the
signal by triggering LePRK2 dephosphorylation followed by dissociation of the
LePRK complex (Wengier et al., PNAS
2003, 6860-6865). We also demonstrated that LePRK2 is hyperphosphorylated in
pollen membranes where some of the phosphorylated residues are important for
pollen tube growth. Using a combination of different
chromatography systems we purified that style component
to homogeneity; it is an extremely stable peptide with a molecular weight
of 3,550 Da. that stimulates pollen tube growth through LePRK2. All these
findings suggest this style peptide is a key element of pollen-pistil signaling
mediated by LePRK2.