Tyrosine Phosphorylation of the Triple Gene Block Protein 3 Regulates Cell-to-Cell Movement and Protein Interactions of Potato Mop-Top Virus

Samuilova, Olga; Santala, Johanna; Valkonen, Jari P. T.

doi:10.1128/jvi.03388-12

Cited by 23 publications

(19 citation statements)

References 58 publications

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“…Although some plant proteins are also modified by both phosphorylation and O-GlcNAcylation (Chen et al, 2005;Taoka et al, 2007;Xing et al, 2009;Xu et al, 2017;Zentella et al, 2016), the interplay of these PTMs in plants is largely unknown. Although several proteins of plant viruses are known to be phosphorylated (Champagne et al, 2007;Hoover et al, 2016;Hu et al, 2015;Hung et al, 2014;Ivanov et al, 2003;Jakubiec et al, 2006;Lee and Lucas, 2001;Link et al, 2011;M odena et al, 2008;Puustinen et al, 2002;Samuilova et al, 2013;Shapka et al, 2005;Zhao et al, 2015), there is evidence that the CP of the potyvirus PPV is both phosphorylated and O-GlcNAcylated (Chen et al, 2005;Fern andez-Fern andez et al, 2002;Subr et al, 2007); this makes this protein an excellent model to study how phosphorylation and O-GlcNAcylation jointly regulate protein activity in plant cells and to define the roles of these PTMs in viral infections.…”

Section: Discussionmentioning

confidence: 99%

Phosphorylation coexists with O‐GlcNAcylation in a plant virus protein and influences viral infection

Martínez-Turiño

Pérez

Hervás

et al. 2018

Molecular Plant Pathology

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Phosphorylation and O-GlcNAcylation are two widespread post-translational modifications (PTMs), often affecting the same eukaryotic target protein. Plum pox virus (PPV) is a member of the genus Potyvirus which infects a wide range of plant species. O-GlcNAcylation of the capsid protein (CP) of PPV has been studied extensively, and some evidence of CP phosphorylation has also been reported. Here, we use proteomics analyses to demonstrate that PPV CP is phosphorylated in vivo at the N-terminus and the beginning of the core region. In contrast with the 'yin-yang' mechanism that applies to some mammalian proteins, PPV CP phosphorylation affects residues different from those that are O-GlcNAcylated (serines Ser-25, Ser-81, Ser-101 and Ser-118). Our findings show that PPV CP can be concurrently phosphorylated and O-GlcNAcylated at nearby residues. However, an analysis using a differential proteomics strategy based on iTRAQ (isobaric tags for relative and absolute quantitation) showed a significant enhancement of phosphorylation at Ser-25 in virions recovered from O-GlcNAcylation-deficient plants, suggesting that crosstalk between O-GlcNAcylation and phosphorylation in PPV CP takes place. Although the preclusion of phosphorylation at the four identified phosphotarget sites only had a limited impact on viral infection, the mimicking of phosphorylation prevents PPV infection in Prunus persica and weakens infection in Nicotiana benthamiana and other herbaceous hosts, prompting the emergence of potentially compensatory second mutations. We postulate that the joint action of phosphorylation and O-GlcNAcylation in the N-proximal segment of CP allows a fine-tuning of protein stability, providing the amount of CP required in each step of viral infection.

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Section: Discussionmentioning

confidence: 99%

Phosphorylation coexists with O‐GlcNAcylation in a plant virus protein and influences viral infection

Martínez-Turiño

Pérez

Hervás

et al. 2018

Molecular Plant Pathology

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“…Furthermore, overexpression of SnRK1 in N. benthamiana plants attenuates virus symptoms and decreases viral DNA accumulation during Y10A/␤ infection, whereas knockdown of SnRK1 results in the reciprocal effects (27). However, little is known about the importance of Tyr phosphorylation of geminivirus proteins, with the exception that Tyr phosphorylation of a pomovirus MP impairs its cell-to-cell movement in plants (53). In this study, we identified two Tyr residues in TYLCCNB-␤C1 that are phosphorylated by SnRK1 (Fig.…”

Section: Discussionmentioning

confidence: 99%

Mimic Phosphorylation of a βC1 Protein Encoded by TYLCCNB Impairs Its Functions as a Viral Suppressor of RNA Silencing and a Symptom Determinant

Zhong

Wang

Xiao

et al. 2017

J Virol

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Phosphorylation of the ␤C1 protein encoded by the betasatellite of tomato yellow leaf curl China virus (TYLCCNB-␤C1) by SNF1-related protein kinase 1 (SnRK1) plays a critical role in defense of host plants against geminivirus infection in Nicotiana benthamiana. However, how phosphorylation of TYLCCNB-␤C1 impacts its pathogenic functions during viral infection remains elusive. In this study, we identified two additional tyrosine residues in TYLCCNB-␤C1 that are phosphorylated by SnRK1. The effects of TYLCCNB-␤C1 phosphorylation on its functions as a viral suppressor of RNA silencing (VSR) and a symptom determinant were investigated via phosphorylation mimic mutants in N. benthamiana plants. Mutations that mimic phosphorylation of TYLCCNB-␤C1 at tyrosine 5 and tyrosine 110 attenuated disease symptoms during viral infection. The phosphorylation mimics weakened the ability of TYLCCNB-␤C1 to reverse transcriptional gene silencing and to suppress posttranscriptional gene silencing and abolished its interaction with N. benthamiana ASYMMETRIC LEAVES 1 in N. benthamiana leaves. The mimic phosphorylation of TYLCCNB-␤C1 had no impact on its protein stability, subcellular localization, or self-association. Our data establish an inhibitory effect of phosphorylation of TYLCCNB-␤C1 on its pathogenic functions as a VSR and a symptom determinant and provide a mechanistic explanation of how SnRK1 functions as a host defense factor. IMPORTANCE Tomato yellow leaf curl China virus (TYLCCNV), which causes a severe yellow leaf curl disease in China, is a monopartite geminivirus associated with the betasatellite (TYLCCNB). TYLCCNB encodes a single pathogenicity protein, ␤C1 (TYLCCNB-␤C1), which functions as both a viral suppressor of RNA silencing (VSR) and a symptom determinant. Here, we show that mimicking phosphorylation of TYLCCNB-␤C1 weakens its ability to reverse transcriptional gene silencing, to suppress posttranscriptional gene silencing, and to interact with N. benthamiana ASYMMETRIC LEAVES 1. To our knowledge, this is the first report establishing an inhibitory effect of phosphorylation of TYLCCNB-␤C1 on its pathogenic functions as both a VSR and a symptom determinant and to provide a mechanistic explanation of how SNF1-related protein kinase 1 acts as a host defense factor. These findings expand the scope of phosphorylation-mediated defense mechanisms and contribute to further understanding of plant defense mechanisms against geminiviruses.KEYWORDS TYLCCNB-␤C1, Nicotiana benthamiana, SnRK1, geminivirus, host defense factor, posttranscriptional gene silencing, protein phosphorylation, transcriptional gene silencing

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“…For example, early studies on Tobacco mosaic virus (TMV) showed that its movement protein (MP) is phosphorylated by a cell wall‐associated kinase that facilitates viral cell‐to‐cell transport through plasmodesmata (Citovsky et al ., ; Karpova et al ., ; Waigmann et al ., ). Phosphorylation of viral movement proteins was then shown to be a common strategy that enables plant viruses to spread (Modena et al ., ; Link et al ., ; Samuilova et al ., ; Hu et al ., ). Various viral proteins with distinct functions are phosphorylated during viral infection, including RNA‐dependent RNA polymerase (RdRp) (Kim et al ., ; Jakubiec et al ., ; Jakubiec & Jupin, ), coat protein (CP) (Ivanov et al ., ; Hung et al ., ; Zhao et al ., ), and proteins that suppress RNA silencing and symptom development (Lewsey et al ., ; Shen et al ., , ; Zhong et al ., ).…”

Section: Introductionmentioning

confidence: 97%

Barley stripe mosaic virus infection requires PKA‐mediated phosphorylation of γb for suppression of both RNA silencing and the host cell death response

Zhang

Dong

et al. 2018

New Phytologist

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The Barley stripe mosaic virus (BSMV) γb protein is a viral suppressor of RNA silencing (VSR) and symptom determinant. However, it is unclear how post-translational modification affects the different functions of γb. Here, we demonstrate that γb is phosphorylated at Ser-96 by a PKA-like kinase in vivo and in vitro. Mutant viruses containing a nonphosphorylatable substitution (BSMV or BSMV ) exhibited reduced viral accumulation in Nicotiana benthamiana due to transient induction of the cell death response that constrained the virus to necrotic areas. By contrast, a BSMV mutant virus that mimics γb phosphorylation spread similarly to the wild-type virus. Furthermore, the S96A mutant had reduced local and systemic γb VSR activity due to having compromised its binding activity to 21-bp dsRNA. However, overexpression of other VSRs in trans or in cis failed to rescue the necrosis induced by BSMV , demonstrating that suppression of cell death by γb phosphorylation is functionally distinct from its RNA silencing suppressor activities. These results provide new insights into the function of γb phosphorylation in regulating RNA silencing and the BSMV-induced host cell death response, and contribute to our understanding of how the virus optimizes the balance between viral replication and virus survival in the host plants during virus infection.

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Tyrosine Phosphorylation of the Triple Gene Block Protein 3 Regulates Cell-to-Cell Movement and Protein Interactions of Potato Mop-Top Virus

Cited by 23 publications

References 58 publications

Phosphorylation coexists with O‐GlcNAcylation in a plant virus protein and influences viral infection

Phosphorylation coexists with O‐GlcNAcylation in a plant virus protein and influences viral infection

Mimic Phosphorylation of a βC1 Protein Encoded by TYLCCNB Impairs Its Functions as a Viral Suppressor of RNA Silencing and a Symptom Determinant

Barley stripe mosaic virus infection requires PKA‐mediated phosphorylation of γb for suppression of both RNA silencing and the host cell death response

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