The geminivirus nuclear shuttle protein is a virulence factor that suppresses transmembrane receptor kinase activity

Abstract

Despite the large number of leucine-rich-repeat (LRR) receptor-like-kinases (RLKs) in plants and their conceptual relevance in signaling events, functional information is restricted to a few family members. Here we describe the characterization of new LRR-RLK family members as virulence targets of the geminivirus nuclear shuttle protein (NSP). NSP interacts specifically with three LRR-RLKs, NIK1, NIK2, and NIK3, through an 80-amino acid region that encompasses the kinase active site and A-loop. We demonstrate that these NSP-interacting kinases (NIKs) are membrane-localized proteins with biochemical properties of signaling receptors. They behave as authentic kinase proteins that undergo autophosphorylation and can also phosphorylate exogenous substrates. Autophosphorylation occurs via an intermolecular event and oligomerization precedes the activation of the kinase. Binding of NSP to NIK inhibits its kinase activity in vitro, suggesting that NIK is involved in antiviral defense response. In support of this, infectivity assays showed a positive correlation between infection rate and loss of NIK1 and NIK3 function. Our data are consistent with a model in which NSP acts as a virulence factor to suppress NIK-mediated antiviral responses.

Virulence Factors of Geminivirus Interact with MYC2 to Subvert Plant Resistance and Promote Vector Performance

“…BV1 in the DNA-B component of CaLCuV is located in a similar genomic locus as the bC1 gene of TYLCCNV/TYLCCNB (Cui et al, 2004;Fontes et al, 2004). Confocal microscopy experiments using BV1-CFP and At-MYC2-YFP showed that the two proteins colocalized in the nucleus (Supplemental Figure 8, fourth panel).…”

Geminivirus Infection Up-Regulates the Expression of Two Arabidopsis Protein Kinases Related to Yeast SNF1- and Mammalian AMPK-Activating Kinases

“…This is achieved in part by modulating existing signal transduction pathways through the interaction of viral proteins and host protein kinases. Geminivirus proteins bind to RLKs that are part of the plant pathogen surveillance system and interfere with the ability of the host to mount a resistance response (Fontes et al, 2004). Susceptibility to geminivirus infection is also enhanced by interaction with an SnRK1, implicating this evolutionarily conserved, energy-sensing protein kinase in the plant defense response (Hao et al, 2003).…”

“…Geminiviruses interact with both types of protein kinase signaling cascades to modulate host processes. The BR1 protein binds to three Leurich-repeat RLKs, NIK1, NIK2, and NIK2, to inhibit their kinase and antiviral activities (Fontes et al, 2004). In contrast, interaction and phosphorylation of BR1 by a PERK-like RLK, NsAK, is necessary for efficient infection and full symptom development (Florentino et al, 2006).…”

Análisis genético de la percepción del ácido salicílico en Arabidopsis thaliana. Caracterización de NRB4

“…Otros efectores virales actúan directamente sobre complejos PRRs. Es el caso de la proteína de transporte nuclear de los geminivirus que es capaz de interaccionar e inhibir la actividad quinasa de tres LRR-RLKs de Arabidopsis necesarias para la respuesta defensiva antiviral (Fontes et al 2004;Speth et al 2007). …”