Publication Information
Mayank et al., 2012
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Abstract
Plant J. 2012 Oct;72(1):89-101. doi: 10.1111/j.1365-313X.2012.05061.x. Epub 2012
Jul 12.
Characterization of the phosphoproteome of mature Arabidopsis pollen.
Mayank P(1), Grossman J, Wuest S, Boisson-Dernier A, Roschitzki B, Nanni P,
Nühse T, Grossniklaus U.
Author information:
(1)Centre for Model Organism Proteomes, University of Zürich, Zürich,
Switzerland.
Successful pollination depends on cell-cell communication and rapid cellular
responses. In Arabidopsis, the pollen grain lands on a dry stigma, where it
hydrates, germinates and grows a pollen tube that delivers the sperm cells to
the female gametophyte to effect double fertilization. Various studies have
emphasized that a mature, dehydrated pollen grain contains all the transcripts
and proteins required for germination and initial pollen tube growth. Therefore,
it is important to explore the role of post-translational modifications (here
phosphorylation), through which many processes induced by pollination are
probably controlled. We report here a phosphoproteomic study conducted on mature
Arabidopsis pollen grains with the aim of identifying potential targets of
phosphorylation. Using three enrichment chromatographies, a broad coverage of
pollen phosphoproteins with 962 phosphorylated peptides corresponding to 598
phosphoproteins was obtained. Additionally, 609 confirmed phosphorylation sites
were successfully mapped. Two hundred and seven of 240 phosphoproteins that were
absent from the PhosPhAt database containing the empirical Arabidopsis
phosphoproteome showed highly enriched expression in pollen. Gene ontology (GO)
enrichment analysis of these 240 phosphoproteins shows an over-representation of
GO categories crucial for pollen tube growth, suggesting that phosphorylation
regulates later processes of pollen development. Moreover, motif analyses of
pollen phosphopeptides showed an over-representation of motifs specific for
Ca²⁺/calmodulin-dependent protein kinases, mitogen-activated protein kinases,
and binding motifs for 14-3-3 proteins. Lastly, one tyrosine phosphorylation
site was identified, validating the TDY dual phosphorylation motif of
mitogen-activated protein kinases (MPK8/MPK15). This study provides a solid
basis to further explore the role of phosphorylation during pollen development.
© 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.
DOI: 10.1111/j.1365-313X.2012.05061.x
PMID: 22631563 [Indexed for MEDLINE]
