Zebrafish is a well-recognized organism for investigating vertebrate development and human diseases. However, the data on zebrafish proteome are scarce, particularly during embryogenesis. This is mostly due to the overwhelming abundance of egg yolk proteins, which tend to mask the detectable presence of less abundant proteins. We developed an efficient procedure to reduce the amount of yolk in zebrafish early embryos to improve the Liquid chromatography–tandem mass spectrometry (LC–MS)-based shotgun proteomics analysis. We demonstrated that the deyolking procedure resulted in a greater number of proteins being identified. This protocol resulted in approximately 2-fold increase in the number of proteins identified in deyolked samples at cleavage stages, and the number of identified proteins increased greatly by 3–4 times compared to non-deyolked samples in both oblong and bud stages. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed a high number of functional proteins differentially accumulated in the deyolked versus non-deyolked samples. The most prominent enrichments after the deyolking procedure included processes, functions, and components related to cellular organization, cell cycle, control of replication and translation, and mitochondrial functions. This deyolking procedure improves both qualitative and quantitative proteome analyses and provides an innovative tool in molecular embryogenesis of polylecithal animals, such as fish, amphibians, reptiles, or birds.
Background
Autophagy is a conserved, highly-regulated catabolic process that plays important roles in growth, development and innate immunity in plants. In this study, we compared the rate of autophagy induction in
Nicotiana benthamiana
plants infected with Tobacco mosaic virus or the TMV 24A + UPD mutant variant, which replicates at a faster rate and induces more severe symptoms. Using a BirA* tag and proximity-dependent biotin identification (BioID) analysis, we identified host proteins that interact with the core autophagy protein, ATG8 in TMV 24A + UPD infected plants. By combining the use of a fast replicating TMV mutant and an in vivo protein-protein screening technique, we were able to gain functional insight into the role of autophagy in a compatible virus-host interaction.
Results
Our study revealed an increased autophagic flux induced by TMV 24A + UPD, as compared to TMV in
N. benthamiana
. Analysis of the functional proteome associated with ATG8 revealed a total of 67 proteins, 16 of which are known to interact with ATG8 or its orthologs in mammalian and yeast systems. The interacting proteins were categorized into four functional groups: immune system process, response to ROS, sulphur amino acid metabolism and calcium signalling. Due to the presence of an ubiquitin-associated (UBA) domain, which is demonstrated to interact with ATG8, the Huntingtin-interacting protein K-like (HYPK) was selected for validation of the physical interaction and function. We used yeast two hybrid (Y2H), bimolecular fluorescence complementation (BiFC) and subcellular localization to validate the ATG8-HYPK interaction. Subsequent down-regulation of ATG8 by virus-induced gene silencing (VIGS) showed enhanced TMV symptoms, suggesting a protective role for autophagy during TMV 24A + UPD infection.
Conclusion
This study presents the use of BioID as a suitable method for screening ATG8 interacting proteins
in planta
. We have identified many putative binding partners of ATG8 during TMV 24A + UPD infection in
N. benthamiana
plants. In addition, we have verified that NbHYPK is an interacting partner of ATG8. We infer that autophagy plays a protective role in TMV 24A + UPD infected plants.
Electronic supplementary material
The online version of this article (10.1186/s12870-019-1930-8) contains supplementary material, which is available to authorized users.
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