ADP-Ribosylation and Antiviral Resistance in Plants

Abstract

ADP-ribosylation (ADPRylation) is a versatile posttranslational modification in eukaryotic cells which is involved in the regulation of a wide range of key biological processes, including DNA repair, cell signalling, programmed cell death, growth and development and responses to biotic and abiotic stresses. Members of the poly(ADP-ribosyl) polymerase (PARP) family play a central role in the process of ADPRylation. Protein targets can be modified by adding either a single ADP-ribose moiety (mono(ADP-ribosyl)ation; MARylation), which is catalysed by mono(ADP-ribosyl) transferases (MARTs or PARP “monoenzymes”), or targets may be decorated with chains of multiple ADP-ribose moieties (PARylation), via the activities of PARP “polyenzymes”. Studies have revealed crosstalk between PARylation (and to a lesser extent, MARylation) processes in plants and plant–virus interactions, suggesting that these tight links may represent a novel factor regulating plant antiviral immunity. From this perspective, we go through the literature linking PARylation-associated processes with other plant regulation pathways controlling virus resistance. Once unraveled, these links may serve as the basis of innovative strategies to improve crop resistance to viruses under challenging environmental conditions which could mitigate yield losses.

Plant Poly(ADP-Ribose) Polymerase 1 Is a Potential Mediator of Cross-Talk between the Cajal Body Protein Coilin and Salicylic Acid-Mediated Antiviral Defence

“…We therefore hypothesize that coilin may play a surveillance role, recognising certain virus proteins (such as TRV 16K), mediating changes in PARP1 localisation pattern and overaccumulation of PARylated proteins, and then promoting defence. It is known that in plants, as in animals, poly(ADP-ribosyl)ation plays an important role in responses to biotic and abiotic stresses [ 1 , 2 , 47 ]. Our experiments using the PARP inhibitor 3AB suggest that PARP1 operates in plant defence, responding to TRV infection by activating SA accumulation and triggering the SA-signalling pathway.…”

“…Poly ADP-ribosylation (PARylation) is a well-known highly conserved posttranslational protein modification. During PARylation, ADP-ribose moieties are typically covalently (or non-covalently) added sequentially to target proteins, leading to decoration of the proteins with poly(ADP-ribose) (PAR) chains of varying length and branching morphology [ 1 , 2 ]. PARylation is carried out by poly(ADP-ribose) polymerases (PARPs), a process which uses nicotinamide adenine dinucleotides (NAD+) as a donor of ADP-ribose for PAR synthesis [ 1 , 2 ].…”

“…During PARylation, ADP-ribose moieties are typically covalently (or non-covalently) added sequentially to target proteins, leading to decoration of the proteins with poly(ADP-ribose) (PAR) chains of varying length and branching morphology [ 1 , 2 ]. PARylation is carried out by poly(ADP-ribose) polymerases (PARPs), a process which uses nicotinamide adenine dinucleotides (NAD+) as a donor of ADP-ribose for PAR synthesis [ 1 , 2 ]. The resultant PARylated proteins, including PARP itself and other protein targets, act as regulators of diverse key biological processes such as DNA repair, programmed cell death and responses to biotic and abiotic stresses and also participate in various other cellular signalling pathways.…”

“…Once the PARylated proteins have fulfilled their regulatory functions, poly(ADP-ribose) glycohydrolases (PARGs) hydrolyse the PAR-chains attached to the proteins, which liberates free PAR or ADP-ribose. Subsequently, free PAR is cleaved into AMP and ribose-5-phosphate via the activity of nucleoside diphosphate linked to some moiety-X (NUDIX) hydrolases [ 1 , 2 ].…”

“…Plant PARP3 has no counterpart in animals, and its functional role remains largely unknown. With regards to plant PARP1 and PARP2, although assumptions concerning their functions have often been inferred by analogy with animal PARPs, the plant-specific roles of these proteins have become apparent [ 1 , 2 ]. In particular, plant PARP1 and PARP2 proteins have been linked to plant responses to biotic and abiotic stresses [ 1 , 17 , 19 ].…”