Satellite RNAs (satRNA) associated with Cucumber mosaic virus (CMV) have been shown to generate multimers during replication. We have discovered that multimers of a CMV satRNA generated in the absence of its helper virus (HV) are... more
Satellite RNAs (satRNA) associated with Cucumber mosaic virus (CMV) have been shown to generate multimers during replication. We have discovered that multimers of a CMV satRNA generated in the absence of its helper virus (HV) are characterized by the addition of a hepta nucleotide motif (HNM) at the monomer junctions. Here, we evaluated the functional significance of HNM in HV-dependent replication by ectopically expressing wild type and mutant forms of satRNA multimers in planta either in (+) or (−)-strand polarity. Comparative replication profiles revealed that (−)-strand multimers with complementary HNM (cHNM) are the preferred initial templates for HV-dependent replication than (−)-strand monomers and multimers lacking the cHNM. Further mutational analyses of the HNM accentuate that preservation of the sequence and native length of HNM is obligatory for efficient replication of satRNA. A model implicating the significance of HNM in HV-dependent production of monomeric and multimeric forms of satRNA is presented.► SatRNA mutilmers with hepta nucleotide motif (HNM) are produced in the absence of its helper virus. ► (−)-strand multimers with HNM are better templates than (−)-strand monomers. ► Preservation of the HNM sequence and length is obligatory for efficient replication.
Satellite RNAs (satRNA) associated with Cucumber mosaic virus (CMV) have been shown to generate multimers during replication. We have discovered that multimers of a CMV satRNA generated in the absence of its helper virus (HV) are... more
Satellite RNAs (satRNA) associated with Cucumber mosaic virus (CMV) have been shown to generate multimers during replication. We have discovered that multimers of a CMV satRNA generated in the absence of its helper virus (HV) are characterized by the addition of a hepta nucleotide motif (HNM) at the monomer junctions. Here, we evaluated the functional significance of HNM in HV-dependent replication by ectopically expressing wild type and mutant forms of satRNA multimers in planta either in (+) or (-)-strand polarity. Comparative replication profiles revealed that (-)-strand multimers with complementary HNM (cHNM) are the preferred initial templates for HV-dependent replication than (-)-strand monomers and multimers lacking the cHNM. Further mutational analyses of the HNM accentuate that preservation of the sequence and native length of HNM is obligatory for efficient replication of satRNA. A model implicating the significance of HNM in HV-dependent production of monomeric and multim...
The phenomenon of rapid turnover of 3’ proximal nucleotides (nt) lost by the action of nuclease in RNA viruses is integral to replication. Here, a set of six deletions (3’Δ3, 3’Δ7, 3’Δ9, 3’Δ13, 3’Δ18 and 3’Δ23), encompassing the 3’ 23 nt... more
The phenomenon of rapid turnover of 3’ proximal nucleotides (nt) lost by the action of nuclease in RNA viruses is integral to replication. Here, a set of six deletions (3’Δ3, 3’Δ7, 3’Δ9, 3’Δ13, 3’Δ18 and 3’Δ23), encompassing the 3’ 23 nt region of a satellite RNA (satRNA) of Cucumber mosaic virus (CMV) strain Q (Q-sat), were engineered. Repair of the 3’ end was not observed in the absence of CMV. However, co-expression with CMV in planta revealed mutants lacking 3’ 18 nt but not 3’ 23 nt are repaired and the progeny accumulation was inversely proportional to the extent of the engineered deletion. Progeny of 3’Δ3 mutant progeny were repaired to wild type (wt) while that of remaining four mutants were heterogeneous, exhibiting a wt secondary structure. Analysis of additional 3’ internal deletions mutants revealed that progeny with a repaired sequence reminiscent of wt secondary structure were competent for replication and systemic spread.
