Quantitative Label-Free Phosphoproteomics of Six Different Life Stages of the Late Blight Pathogen Phytophthora infestans Reveals Abundant Phosphorylation of Members of the CRN Effector Family

The oomycete Phytophthora
infestans is the causal agent of late blight in potato
and tomato. Since the
underlying processes that govern pathogenicity and development in P. infestans are largely unknown, we have performed
a large-scale phosphoproteomics study of six different P. infestans life stages. We have obtained quantitative
data for 2922 phosphopeptides and compared their abundance. Life-stage-specific
phosphopeptides include ATP-binding cassette transporters and a kinase
that only occurs in appressoria. In an extended data set, we identified
2179 phosphorylation sites and deduced 22 phosphomotifs. Several of
the phosphomotifs matched consensus sequences of kinases that occur
in P. infestans but not Arabidopsis. In addition, we detected tyrosine phosphopeptides
that are potential targets of kinases resembling mammalian tyrosine
kinases. Among the phosphorylated proteins are members of the RXLR
and Crinkler effector families. The latter are phosphorylated in several
life stages and at multiple positions, in sites that are conserved
between different members of the Crinkler family. This indicates that
proteins in the Crinkler family have functions beyond their putative
role as (necrosis-inducing) effectors. This phosphoproteomics data
will be instrumental for studies on oomycetes and host–oomycete
interactions. The data sets have been deposited to ProteomeXchange
(identifier PXD000433).