Location: Wheat, Sorghum and Forage ResearchTitle: Characterization of the 5’- and 3’-terminal subgenomic RNAs produced by a capillovirus: evidence for a CP subgenomic RNA) Author
|Tatineni, Satyanarayana - Ts|
Submitted to: Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2008
Publication Date: 3/13/2009
Publication URL: hdl.handle.net/10113/29280
Citation: Tatineni, S., Afunian, M.R., Gowda, S., Hilf, M.E., Bar-Joseph, M., Dawson, W.O. 2009. Characterization of the 5’- and 3’-terminal subgenomic RNAs produced by a capillovirus: evidence for a CP subgenomic RNA. Virology 385 (2009) 521–528. Interpretive Summary: Citrus tatter leaf virus (CTLV), a member of the Capillovirus genus of Flexiviridae family, induces a budunion incompatibility of citrus trees grafted on trifoliate or its hybrids, which are leading rootstocks in US and worldwide. Molecular biology and genome expression strategy of CTLV was poorly examined. In this study, the genome expression strategy of CTLV was examined and found that CTLV produces two 3’-terminal sgRNAs for the expression of movement protein (ORF2) and coat protein (located in the 3’ end of ORF1). In addition to these two 3’-terminal sgRNAs, CTLV also produces two 5’-terminal sgRNAs corresponding to two of its 3’-terminal sgRNAs. This study suggests that CTLV produces a dedicated 3’-sgRNA for the expression of its CP, even though the CP is located as part of the replicase in the 3’ end of ORF1.
Technical Abstract: The members of Capillovirus genus encode two overlapping open reading frames (ORFs): ORF1 encodes a large polyprotein containing the domains of replication-associated proteins plus a coat protein (CP), and ORF2 encodes a movement protein, located within ORF1 in a different reading frame. Organization of the CP sequence as part of the replicase ORF is unusual in capilloviruses. In this study, we examined the capillovirus genome expression strategy by characterizing viral RNAs produced by the Meyer lemon isolate of Citrus tatter leaf virus (CTLV-ML), a Capillovirus. CTLV-ML produced a genome length RNA and two 3’-terminal sgRNAs (3’-sgRNAs) in infected tissue that contain the MP gene and CP coding sequence (3’-sgRNA1), and the CP coding sequence (3’-sgRNA2), respectively. Both 3’-sgRNAs initiate at a conserved octanucleotide (UUGAAAGA) and are 1826 (3’-sgRNA1) and 869 (3’-sgRNA2) nts with 119 and 15 nt leader sequences, respectively, suggesting that these two 3’-sgRNAs could serve to express the MP and CP. Additionally, accumulation of two 5’-terminal sgRNAs of 5586 (5’-sgRNA1) and 4625 (5’-sgRNA2) nts, which are colinear with the genomic RNA was observed. The 3’ termini of the 5’-sgRNAs 1 and 2 mapped to 38-40 and 38-44 nts upstream of the transcription start sites of 3’-sgRNAs 2 and 1, respectively, and possibly are produced by termination of genomic RNA synthesis at the promoter regions of the 3’-sgRNAs. The presence of a separate 3’-sgRNA corresponding to the CP coding sequence and its cognate 5’-terminal sgRNA (5’-sgRNA1) suggests that CTLV-ML produces a dedicated sgRNA for the expression of its CP.