A Begomovirus DNAβ-Encoded Protein Binds DNA, Functions as a Suppressor of RNA Silencing, and Targets the Cell Nucleus

Cui, Xiaofeng; Li, Guixin; Wang, Daowen; Hu, Dongwei; Zhou, Xueping

doi:10.1128/jvi.79.16.10764-10775.2005

Cited by 258 publications

(192 citation statements)

References 62 publications

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“…We showed previously that the bC1 protein binds to DNA in a sequence-nonspecific manner, functions as a suppressor of RNA silencing, and is a pathogenicity protein that plays a vital role in symptom induction by suppression of the silencing defenses in plants (Cui et al, 2005). Phosphorylation of proteins can regulate their nucleic acid-binding properties (Boyle et al, 1991;Mayrand et al, 1993) and interactions between viral RNA and replication proteins of positive-strand RNA viruses (Shapka et al, 2005;Stork et al, 2005).…”

Section: Discussionmentioning

confidence: 99%

“…Full-length b-satellite molecules encode an approximately 13.5-kD protein known as bC1 on the complementary sense strand. bC1 is a pathogenicity determinant and a suppressor of RNA silencing (Jose and Usha, 2003;Cui et al, 2004Cui et al, , 2005Saunders et al, 2004;Qian and Zhou, 2005;Saeed et al, 2005;Gopal et al, 2007;Kon et al, 2007). Previous studies showed that bC1 interacts with ASYMMETRIC LEAVES1 to alter leaf development and suppress selected jasmonic acid responses (Yang et al, 2008).…”

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confidence: 99%

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

et al. 2011

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The bC1 protein of tomato yellow leaf curl China b-satellite functions as a pathogenicity determinant. To better understand the molecular basis of bC1 in pathogenicity, a yeast two-hybrid screen of a tomato (Solanum lycopersicum) cDNA library was carried out using bC1 as bait. bC1 interacted with a tomato SUCROSE-NONFERMENTING1-related kinase designated as SlSnRK1. Their interaction was confirmed using a bimolecular fluorescence complementation assay in Nicotiana benthamiana cells. Plants overexpressing SnRK1 were delayed for symptom appearance and contained lower levels of viral and satellite DNA, while plants silenced for SnRK1 expression developed symptoms earlier and accumulated higher levels of viral DNA. In vitro kinase assays showed that bC1 is phosphorylated by SlSnRK1 mainly on serine at position 33 and threonine at position 78. Plants infected with bC1 mutants containing phosphorylation-mimic aspartate residues in place of serine-33 and/or threonine-78 displayed delayed and attenuated symptoms and accumulated lower levels of viral DNA, while plants infected with phosphorylation-negative alanine mutants contained higher levels of viral DNA. These results suggested that the SlSnRK1 protein attenuates geminivirus infection by interacting with and phosphorylating the bC1 protein.

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Section: Discussionmentioning

confidence: 99%

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

et al. 2011

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“…Betasatellites are required for the development of wild-type symptoms in naturally infected hosts and enhance helper begomoviral pathogenicity by modulating host defences Jose & Usha, 2003;Zhou et al, 2003;Saunders et al, 2004;Cui et al, 2005;Idris et al, 2005;Saeed et al, 2005). A major distinction between the two satellite types is that alphasatellites are thought to be dispensable and do not contribute to disease development (Saunders et al, 2000;Briddon et al, 2004;Briddon & Stanley, 2006).…”

Section: Introductionmentioning

confidence: 99%

An unusual alphasatellite associated with monopartite begomoviruses attenuates symptoms and reduces betasatellite accumulation

Idris

Shahid

Briddon

et al. 2010

Journal of General Virology

163

120

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The Oman strain of Tomato yellow leaf curl virus (TYLCV-OM) and its associated betasatellite, an isolate of Tomato leaf curl betasatellite (ToLCB), were previously reported from Oman. Here we report the isolation of a second, previously undescribed, begomovirus [Tomato leaf curl Oman virus (ToLCOMV)] and an alphasatellite from that same plant sample. This alphasatellite is closely related (90 % shared nucleotide identity) to an unusual DNA-2-type Ageratum yellow vein Singapore alphasatellite (AYVSGA), thus far identified only in Singapore. ToLCOMV was found to have a recombinant genome comprising sequences derived from two extant parents, TYLCV-OM, which is indigenous to Oman, and Papaya leaf curl virus from the Indian subcontinent. All possible combinations of ToLCOMV, TYLCV-OM, ToLCB and AYVSGA were used to agro-inoculate tomato and Nicotiana benthamiana. Infection with ToLCOMV yielded mild leaf-curl symptoms in both hosts; however, plants inoculated with TYLCV-OM developed more severe symptoms. Plants infected with ToLCB in the presence of either helper begomovirus resulted in more severe symptoms. Surprisingly, symptoms in N. benthamiana infected with the alphasatellite together with either of the helper viruses and the betasatellite were attenuated and betasatellite DNA accumulation was substantially reduced. However, in the latter plants no concomitant reduction in the accumulation of helper virus DNA was observed. This is the first example of an attenuation of begomovirus-betasatellite symptoms by this unusual class of alphasatellites. This observation suggests that some DNA-2 alphasatellites encode a pathogenicity determinant that may modulate begomovirus-betasatellite infection by reducing betasatellite DNA accumulation.

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“…Betasatellites typically contain a satellite conserved region (SCR), an adenine-rich region and a bC1 ORF. The bC1 ORF has been characterized as a pathogenicity determinant that suppresses host antiviral silencing and is involved in virus movement (Cui et al, 2005;Li et al, 2014;Saunders et al, 2004;Yang et al, 2011). A class of autonomously replicating satellite-like molecules identified as alphasatellites require helper begomoviruses for their intra-and intercellular movement and are reported to ameliorate symptoms in a few cases (Idris et al, 2011;Nawaz-ulRehman et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Complexity of begomovirus and betasatellite populations associated with chilli leaf curl disease in India

Kumar

Singh

Yadav

et al. 2015

Journal of General Virology

102

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Chilli, which encompasses several species in the genus Capsicum, is widely consumed throughout the world. In the Indian subcontinent, production of chilli is constrained due to chilli leaf curl disease (ChiLCD) caused by begomoviruses. Despite the considerable economic consequences of ChiLCD on chilli cultivation in India, there have been scant studies of the genetic diversity and structure of the begomoviruses that cause this disease. Here we report on a comprehensive survey across major chilli-growing regions in India. Analysis of samples collected in the survey indicates that ChiLCD-infected plants are associated with a complex of begomoviruses (including one previously unreported species) with a diverse group of betasatellites found in crops and weeds. The associated betasatellites neither enhanced the accumulation of the begomovirus components nor reduced the incubation period in Nicotiana benthamiana. The ChiLCD-associated begomoviruses induced mild symptoms on Capsicum spp., but both the level of helper virus that accumulated and the severity of symptoms were increased in the presence of cognate betasatellites. Interestingly, most of the begomoviruses were found to be intra-species recombinants. The betasatellites possess high nucleotide variability, and recombination among them was also evident. The nucleotide substitution rates were determined for the AV1 gene of begomoviruses (2.60610 23 substitutions site 21 year 21 ) and the bC1 gene of betasatellites [chilli leaf curl betasatellite (ChiLCB), 2.57610 24 substitution site 21 year 21 ; tomato leaf curl Bangladesh betasatellite (ToLCBDB), 5.22610 24 substitution site 21 year 21 ]. This study underscores the current understanding of Indian ChiLCD-associated begomoviruses and also demonstrates the crucial role of betasatellites in severe disease development in Capsicum spp.

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A Begomovirus DNAβ-Encoded Protein Binds DNA, Functions as a Suppressor of RNA Silencing, and Targets the Cell Nucleus

Cited by 258 publications

References 62 publications

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

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

An unusual alphasatellite associated with monopartite begomoviruses attenuates symptoms and reduces betasatellite accumulation

Complexity of begomovirus and betasatellite populations associated with chilli leaf curl disease in India

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