Characterization of the TMV encapsidation initiation site on 18S rRNA.

AUTOR(ES)

Gaddipati, J P

RESUMO

Tobacco Mosaic Virus capsid protein oligomers react with and encapsidate 18S rRNA from both plant and mammalian sources in vitro. The site (ei) in 18S rRNA which reacts with capsid protein to initiate the packaging reaction has been localized and partially characterized by testing the ability of transcripts from different regions of a cloned Cucurbita pepo rDNA repeat unit to become encapsidated. The 18S rRNA ei is found to react more slowly with capsid protein than does the functional virion ei and to lie within a 43 nucleotide region which starts at position 157 from the 5' terminus of 18S rRNA. When 6 nucleotides are removed from the 5' end, the remaining 37 nucleotide segment is still reactive, but with reduced efficiency. The primary structure of the reactive segment has limited similarity to the virion ei and can be folded into a stem-loop. The first 18 nucleotides of the ei region is highly conserved from an evolutionary standpoint and this may account for the ability of 18S rRNAs from both plant and mammalian sources to be encapsidated.

Documentos Relacionados

• Nucleotide sequence encoding the 5' end of Xenopus laevis 18S rRNA.
• Structure of mouse rRNA precursors. Complete sequence and potential folding of the spacer regions between 18S and 28S rRNA.
• Two distinct recognition signals define the site of endonucleolytic cleavage at the 5'-end of yeast 18S rRNA.
• Intermolecular mRNA-rRNA hybridization and the distribution of potential interaction regions in murine 18S rRNA.
• 18S rRNA processing requires the RNA helicase-like protein Rrp3.