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Phosphorylation of TGB1 by protein kinase CK2 promotes barley stripe mosaic virus movement in monocots and dicots.

Hu Y, Li Z, Yuan C, Jin X, Yan L, Zhao X, Zhang Y, Jackson AO, Wang X, Han C, Yu J, Li D - J. Exp. Bot. (2015)

Bottom Line: Substitution of Thr-395 or Thr-401 with aspartic acid interfered with monocot and dicot cell-to-cell movement and the plants failed to develop systemic infections.The mutant XJTGB1T395A/T401A weakened in vitro interactions between XJTGB1 and XJTGB3 proteins but had little effect on XJTGB1 RNA-binding ability.Taken together, our results support a critical role of CK2 phosphorylation in the movement of BSMV in monocots and dicots, and provide new insights into the roles of phosphorylation in TGB protein functions.

View Article: PubMed Central - PubMed

Affiliation: State Key laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.

No MeSH data available.


Related in: MedlinePlus

Effects of XJTGB1 protein phosphorylation on XJBSMV cell-to-cell movement in N. benthamiana and barley. (A) Fluorescence in N. benthamiana leaves at 3 dpi with an Agrobacterium mixture of pCa-αND, pCa-γND:GFP, and pCa-βXJ or the pCa-βXJ mutant derivatives. The total bacterial concentrations for infiltration were OD600 of 0.08. (B) Fluorescence in barley leaves at 3 dpi with in vitro transcripts of RNAα and RNAγ:GFP plus wt XJRNAβ or the XJRNAβ phosphorylation site mutant derivatives. Bars represent 500 μm. (This figure is available in colour at JXB online.)
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Figure 6: Effects of XJTGB1 protein phosphorylation on XJBSMV cell-to-cell movement in N. benthamiana and barley. (A) Fluorescence in N. benthamiana leaves at 3 dpi with an Agrobacterium mixture of pCa-αND, pCa-γND:GFP, and pCa-βXJ or the pCa-βXJ mutant derivatives. The total bacterial concentrations for infiltration were OD600 of 0.08. (B) Fluorescence in barley leaves at 3 dpi with in vitro transcripts of RNAα and RNAγ:GFP plus wt XJRNAβ or the XJRNAβ phosphorylation site mutant derivatives. Bars represent 500 μm. (This figure is available in colour at JXB online.)

Mentions: The localized movement in infiltrated N. benthamiana leaves generally reflected the systemic infection phenotypes elicited by the mutants (Fig. 6A). In N. benthamiana, the wt βXJ and βXJ-TGB1T395A mutant both exhibited cell-to-cell movement encompassing several cells at 3 dpi (Fig. 6A), as expected due to their ability to elicit systemic infections. The remaining mutants usually developed fluorescence in a single cell or rarely in two to three adjacent cells (Fig. 6A). Hence, the localized movements of the mutants correlated reasonably well with their systemic movement patterns in N. benthamiana. In barley leaves, most of the fluorescence at 3 dpi appeared in mesophyll cells, but in this case, the virus had to traverse only two to three cell layers before encountering the closely aligned parallel vasculature (Fig. 6B). Hence, the βXJ-TGB1T395A, βXJ-TGB1T395E, and βXJ-TGB1T401A mutants that established systemic infections in barley and wheat needed to negotiate only a limited number of mesophyll cells to reach the vascular elements for systemic spread, whereas movement through a larger number of cells was required to reach the dicot vasculature. The other mutants, βXJ-TGB1T395D, βXJ-TGB1T401D, and βXJ-TGB1T395A/T401A, exhibited more limited cell-to-cell movement compared with βXJ-TGB1T395A, βXJ-TGB1T395E, and βXJ-TGB1T401A, but could spread to a few adjacent cells. However, these three mutants were unable to invade the upper cereal leaves. Hence, these results demonstrate that phosphorylation activities at Thr-395 and Thr-401 differentially affecte systemic movement in monocot versus dicot hosts and suggest that at least some of the host-specific results may be a consequence of the vasculature architecture of these hosts.


Phosphorylation of TGB1 by protein kinase CK2 promotes barley stripe mosaic virus movement in monocots and dicots.

Hu Y, Li Z, Yuan C, Jin X, Yan L, Zhao X, Zhang Y, Jackson AO, Wang X, Han C, Yu J, Li D - J. Exp. Bot. (2015)

Effects of XJTGB1 protein phosphorylation on XJBSMV cell-to-cell movement in N. benthamiana and barley. (A) Fluorescence in N. benthamiana leaves at 3 dpi with an Agrobacterium mixture of pCa-αND, pCa-γND:GFP, and pCa-βXJ or the pCa-βXJ mutant derivatives. The total bacterial concentrations for infiltration were OD600 of 0.08. (B) Fluorescence in barley leaves at 3 dpi with in vitro transcripts of RNAα and RNAγ:GFP plus wt XJRNAβ or the XJRNAβ phosphorylation site mutant derivatives. Bars represent 500 μm. (This figure is available in colour at JXB online.)
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Related In: Results  -  Collection

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Figure 6: Effects of XJTGB1 protein phosphorylation on XJBSMV cell-to-cell movement in N. benthamiana and barley. (A) Fluorescence in N. benthamiana leaves at 3 dpi with an Agrobacterium mixture of pCa-αND, pCa-γND:GFP, and pCa-βXJ or the pCa-βXJ mutant derivatives. The total bacterial concentrations for infiltration were OD600 of 0.08. (B) Fluorescence in barley leaves at 3 dpi with in vitro transcripts of RNAα and RNAγ:GFP plus wt XJRNAβ or the XJRNAβ phosphorylation site mutant derivatives. Bars represent 500 μm. (This figure is available in colour at JXB online.)
Mentions: The localized movement in infiltrated N. benthamiana leaves generally reflected the systemic infection phenotypes elicited by the mutants (Fig. 6A). In N. benthamiana, the wt βXJ and βXJ-TGB1T395A mutant both exhibited cell-to-cell movement encompassing several cells at 3 dpi (Fig. 6A), as expected due to their ability to elicit systemic infections. The remaining mutants usually developed fluorescence in a single cell or rarely in two to three adjacent cells (Fig. 6A). Hence, the localized movements of the mutants correlated reasonably well with their systemic movement patterns in N. benthamiana. In barley leaves, most of the fluorescence at 3 dpi appeared in mesophyll cells, but in this case, the virus had to traverse only two to three cell layers before encountering the closely aligned parallel vasculature (Fig. 6B). Hence, the βXJ-TGB1T395A, βXJ-TGB1T395E, and βXJ-TGB1T401A mutants that established systemic infections in barley and wheat needed to negotiate only a limited number of mesophyll cells to reach the vascular elements for systemic spread, whereas movement through a larger number of cells was required to reach the dicot vasculature. The other mutants, βXJ-TGB1T395D, βXJ-TGB1T401D, and βXJ-TGB1T395A/T401A, exhibited more limited cell-to-cell movement compared with βXJ-TGB1T395A, βXJ-TGB1T395E, and βXJ-TGB1T401A, but could spread to a few adjacent cells. However, these three mutants were unable to invade the upper cereal leaves. Hence, these results demonstrate that phosphorylation activities at Thr-395 and Thr-401 differentially affecte systemic movement in monocot versus dicot hosts and suggest that at least some of the host-specific results may be a consequence of the vasculature architecture of these hosts.

Bottom Line: Substitution of Thr-395 or Thr-401 with aspartic acid interfered with monocot and dicot cell-to-cell movement and the plants failed to develop systemic infections.The mutant XJTGB1T395A/T401A weakened in vitro interactions between XJTGB1 and XJTGB3 proteins but had little effect on XJTGB1 RNA-binding ability.Taken together, our results support a critical role of CK2 phosphorylation in the movement of BSMV in monocots and dicots, and provide new insights into the roles of phosphorylation in TGB protein functions.

View Article: PubMed Central - PubMed

Affiliation: State Key laboratory of Agro-Biotechnology and Ministry of Agriculture Key Laboratory of Soil Microbiology, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China.

No MeSH data available.


Related in: MedlinePlus