Model System-Guided Protein Interaction Mapping for Virus Isolated from Phloem Tissue

Phloem
localization of plant viruses is advantageous for acquisition by sap-sucking
vectors but hampers host–virus protein interaction studies.
In this study, Potato leafroll virus (PLRV)–host protein complexes
were isolated from systemically infected potato, a natural host of
the virus. Comparing two different co-immunoprecipitation (co-IP)
support matrices coupled to mass spectrometry (MS), we identified
44 potato proteins and one viral protein (P1) specifically associated
with virus isolated from infected phloem. An additional 142 proteins
interact in complex with virus at varying degrees
of confidence. Greater than 80% of these proteins were previously
found to form high confidence interactions with PLRV isolated from
the model host Nicotiana benthamiana. Bioinformatics
revealed that these proteins are enriched for functions related to
plasmodesmata, organelle membrane transport, translation, and mRNA
processing. Our results show that model system proteomics experiments
are extremely valuable for understanding protein interactions regulating
infection in recalcitrant pathogens such as phloem-limited viruses.