A geminivirus replication protein interacts with the retinoblastoma protein through a novel domain to determine symptoms and tissue specificity of infection in plants

Abstract

contributed equally to this work Geminiviruses replicate in nuclei of mature plant cells after inducing the accumulation of host DNA replication machinery. Earlier studies showed that the viral replication factor, AL1, is suf®cient for host induction and interacts with the cell cycle regulator, retinoblastoma (pRb). Unlike other DNA virus proteins, AL1 does not contain the pRb binding consensus, LXCXE, and interacts with plant pRb homologues (pRBR) through a novel amino acid sequence. We mapped the pRBR binding domain of AL1 between amino acids 101 and 180 and identi®ed two mutants that are differentially impacted for AL1± pRBR interactions. Plants infected with the E-N140 mutant, which is wild-type for pRBR binding, developed wild-type symptoms and accumulated viral DNA and AL1 protein in epidermal, mesophyll and vascular cells of mature leaves. Plants inoculated with the KEE146 mutant, which retains 16% pRBR binding activity, only developed chlorosis along the veins, and viral DNA, AL1 protein and the host DNA synthesis factor, proliferating cell nuclear antigen, were localized to vascular tissue. These results established the importance of AL1±pRBR interactions during geminivirus infection of plants.

Tomato SlSnRK1 Protein Interacts with and Phosphorylates βC1, a Pathogenesis Protein Encoded by a Geminivirus β-Satellite

“…In response, the plant hosts have evolved diverse innate defense mechanisms to counter these challenges (Voinnet, 2001;Xie and Guo, 2006). Many host factors have been shown to be hijacked or coopted by geminiviruses to facilitate infection (Kong et al, 2000;Egelkrout et al, 2001;Carvalho et al, 2008a). In contrast, few host factors have been shown to participate in plant antiviral processes.…”

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

“…AL1 interacts with the host pRBR to induce the expression of DNA replication machinery and cause mature plant cells to reenter the S phase of cell cycle (Ach et al, 1997;Kong et al, 2000;Nagar et al, 2002). Because GRIK1 and GRIK2 also interact with AL1, we asked if their expression is developmentally regulated, suggestive of intrinsic functions associated with DNA synthesis or differentiation.…”

“…AL1 and AL3 interact with the retinoblastoma-related protein (pRBR), a negative regulator of cell cycle progression and a differentiation factor (Weinberg, 1995;Ach et al, 1997;Kong et al, 2000). The AL1-pRBR interaction interferes with pRBR binding to the cell cycle-associated E2F transcription factors and leads to the activation of genes encoding proteins required for DNA replication (Egelkrout et al, 2001;Desvoyes et al, 2006).…”

Regulation of theChlamydomonasCell Cycle by a Stable, Chromatin-Associated Retinoblastoma Tumor Suppressor Complex

“…RB-related proteins (RBRs) have been identified in embyrophytes (vascular and nonvascular land plants) and green algae (Xie et al, 1996;Ach et al, 1997;Kong et al, 2000;Umen and Goodenough, 2001;Dewitte and Murray, 2003;Robbens et al, 2005;Sabelli et al, 2005;Inze and De Veylder, 2006;Ferris et al, 2010). Embryophyte RBRs are cell cycle-regulated phosphoproteins (Huntley et al, 1998;Boniotti and Gutierrez, 2001;Sabelli et al, 2005) that bind E2Fs (Huntley et al, 1998;Ramírez-Parra et al, 1999Sekine et al, 1999;Sabelli et al, 2005).…”