Correlation between structure and pathogenicity of potato spindle tuber viroid (PSTV)

AUTOR(ES)

Schnölzer, Martina

RESUMO

Sequence analysis by primer-extension at the level of their cDNA showed that the RNA genomes of various field isolates of potato spindle tuber viroid (PSTV) of different virulence differ from each other only in a few nucleotides in two distinct regions of the rod-shaped molecule. Despite insertions and deletions the chain length of 359 nucleotides is strictly conserved in all the isolates studied. Thermodynamic calculations revealed that due to the observed sequence differences the region located at the left hand part of the rod-like secondary structure of the PSTV molecule, denoted `virulence modulating (VM) region', becomes increasingly unstable with the increasing virulence of the corresponding isolate. Based on these data we propose in molecular terms a model for the mechanism of viroid pathogenicity. It implies that the nucleotides of the VM region specify and modulate the binding- and hence the competition-potential of the PSTV RNA molecule for a still unknown host factor(s) and thus determine the virulence of PSTV.

Documentos Relacionados

• Infectivity studies on different potato spindle tuber viroid (PSTV) RNAs synthesized in vitro with the SP6 transcription system
• Cloned single- and double-stranded DNA copies of potato spindle tuber viroid (PSTV) RNA and co-inoculated subgenomic DNA fragments are infectious.
• Linear oligomeric potato spindle tuber viroid (PSTV) RNAs are accurately processed in vitro to the monomeric circular viroid proper when incubated with a nuclear extract from healthy potato cells
• Mutational analysis of potato spindle tuber viroid reveals complex relationships between structure and infectivity
• RNA intermediates in potato spindle tuber viroid replication