Common and Strain-Specific Post-Translational Modifications of the Potyvirus Plum pox virus Coat Protein in Different Hosts

Abstract

Phosphorylation and O-GlcNAcylation are widespread post-translational modifications (PTMs), often sharing protein targets. Numerous studies have reported the phosphorylation of plant viral proteins. In plants, research on O-GlcNAcylation lags behind that of other eukaryotes, and information about O-GlcNAcylated plant viral proteins is extremely scarce. The potyvirus Plum pox virus (PPV) causes sharka disease in Prunus trees and also infects a wide range of experimental hosts. Capsid protein (CP) from virions of PPV-R isolate purified from herbaceous plants can be extensively modified by O-GlcNAcylation and phosphorylation. In this study, a combination of proteomics and biochemical approaches was employed to broaden knowledge of PPV CP PTMs. CP proved to be modified regardless of whether or not it was assembled into mature particles. PTMs of CP occurred in the natural host Prunus persica, similarly to what happens in herbaceous plants. Additionally, we observed that O-GlcNAcylation and phosphorylation were general features of different PPV strains, suggesting that these modifications contribute to general strategies deployed during plant-virus interactions. Interestingly, phosphorylation at a casein kinase II motif conserved among potyviral CPs exhibited strain specificity in PPV; however, it did not display the critical role attributed to the same modification in the CP of another potyvirus, Potato virus A.

Demystifying the O-GlcNAc Code: A Systems View

“…93−95 Furthermore, O-GlcNAcylation occurs on the capsid protein (CP) from virions of PPV, regardless of whether or not it is assembled into mature particles. 96 Besides the natural PPV host P. persica, O-GlcNAcylation of capsid protein has been observed in herbaceous plants (even evolutionarily distant hosts), 96 suggesting that O-GlcNAcylation is likely a general feature of different PPV strains.…”

“…PPV is a potyvirus (with single-stranded genomic RNA) that infects a wide range of plant species. A number of O-GlcNAc sites have been identified on the capsid protein (CP) of PPV, with concurrent phosphorylation at nearby residues. − It appears that there is crosstalk between the two PTMs on certain sites, which may finely tune viral infection and other functions. − Furthermore, O-GlcNAcylation occurs on the capsid protein (CP) from virions of PPV, regardless of whether or not it is assembled into mature particles . Besides the natural PPV host P. persica , O-GlcNAcylation of capsid protein has been observed in herbaceous plants (even evolutionarily distant hosts), suggesting that O-GlcNAcylation is likely a general feature of different PPV strains.…”

Functional Characterization of Pepper Vein Banding Virus-Encoded Proteins and Their Interactions: Implications in Potyvirus Infection

“…It has been reported in many proteins that glycosylation reverses the effect of phosphorylation [35]. The O-glycosylation of the coat protein of plum pox virus (PPV) has been shown to enhance viral infection [36]. Thus, these closely related post-translational modifications could likely regulate the assembly/disassembly of potyviruses.…”

“…Similarly, CP also inhibits the potyviral RNA translation during the late stages of the infection so that more RNA is available for encapsidation and thus facilitating the assembly of the virus [80]. Potyviral proteins are also subjected to post-translation modifications such as phosphorylation (VPg, NIa-Pro and CP), glycosylation (CP) and SUMOylation (NIb) [33,36,[81][82][83] which forms another line of regulation during the viral life-cycle.…”

Special Issue: “The Complexity of the Potyviral Interaction Network”

“…The binding of eIF(iso)4E to VPg is proposed to mediate RNA stabilization, transfer to the RNA silencing suppression pathway, and further to polysomes for viral protein synthesis [ 3 ]. The study of Hervás et al [ 4 ] illustrates how post-translational modifications of potyviral capsid protein through O-GlcNAcylation and phosphorylation in herbaceous and ligneous hosts may contribute to both general and strain-specific strategies deployed during plant–virus interactions. The study of Sabharwal and Savithri highlights the role of intrinsically disordered domains in the multiple functions of potyviral proteins and describes how potyvirus-like particles can be used as nanocarriers for biomedical applications [ 5 ].…”