Crucial role of the 5' conserved structure of bamboo mosaic virus satellite RNA in downregulation of helper viral RNA replication.
Satellite RNA of Bamboo mosaic virus (satBaMV), a single-stranded mRNA type satellite encoding a protein of 20 kDa (P20), depends on the helper BaMV for replication and encapsidation. Two satBaMV isolates, BSF4 and BSL6, exhibit distinctly differential phenotypes in Nicotiana benthamiana plants when coinoculated with BaMV RNA. BSL6 significantly reduces BaMV RNA replication and suppresses the BaMV-induced symptoms, whereas BSF4 does not. By studies with chimeric satBaMVs generated by exchanging the components between BSF4 and BSL6, the genetic determinants responsible for the downregulation of BaMV replication and symptom expression were mapped at the 5' untranslated region (UTR) of BSL6. The 5' UTR of BSL6 alone is sufficient to diminish BaMV RNA replication when the 5' UTR is inserted in cis into the BaMV expression vector or when coinoculation with mutants that block the synthesis of P20 protein takes place. Further, the 5' UTR of natural satBaMV isolates contains one hypervariable (HV) region which folds into a conserved apical hairpin stem-loop (AHSL) structure (W. B. Yeh, Y. H. Hsu, H. C. Chen, and N. S. Lin, Virology 330:105-115, 2004). Interchanges of AHSL segment of HV regions between BSF4 and BSL6 led to the ability of chimeric satBaMV to interfere with BaMV replication and symptom expression. The conserved secondary structure within the HV region is a potent determinant of the downregulation of helper virus replication.
Hsu
Yau-Heiu
YH
Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan, Republic of China.
Chen
Hsin-Chuan
HC
Cheng
Jeannie
J
Annamalai
Padmanaban
P
Annamali
Padmanaban
P
Lin
Bin-Yen
BY
Wu
Chiang-Tai
CT
Yeh
Wen-Bin
WB
Lin
Na-Sheng
NS
D020121:5' Untranslated Regions / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D015536:Down-Regulation; D006378:Helper Viruses / Q000502:physiology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010935:Plant Diseases / Q000821:virology; D017863:Potexvirus / Q000235:genetics / Q000502:physiology*; D019244:RNA, Satellite / Q000235:genetics* / Q000502:physiology; D012367:RNA, Viral / Q000235:genetics* / Q000502:physiology; D014026:Nicotiana / Q000821:virology; D014779:Virus Replication / Q000235:genetics*
D020121:5' Untranslated Regions; D019244:RNA, Satellite; D012367:RNA, Viral