Molecular biology
VIRION
Virions are icosahedral T = 9 and might be enveloped.
Structure of the Ty3/Gypsy retrotransposon capsid and the evolution of retroviruses
Svetlana O Dodonova, Simone Prinz, Virginia Bilanchone, Suzanne Sandmeyer, John A G Briggs
Proc Natl Acad Sci U S A. 2019 May 14;116(20):10048-10057.
Proc Natl Acad Sci U S A. 2019 May 14;116(20):10048-10057.
GENOME
Monopartite, linear, dimeric, ssRNA(+) genome of about 7-11 kb
GENE EXPRESSION
The integrated transposon utilizes the promoter elements in the 5' LTR to drive transcription primed with a host-encoded tRNA. This gives rise to the full length mRNA that will serve as genomic RNA to be packaged into virions or used as a template for translation of gag and gag-pol (1 ribosomal frameshift) polyproteins.
ENZYMES
- Reverse transcriptase
- RNAse H [RT]
- Polyprotein protease (Peptidase A) [PRO]
- Integrase [INT]
REPLICATION
- Transcription of retrotransposon to form viral RNAs.
- Translation of the RNAs to form precursor polyproteins.
- Assembly of the virion and packaging of the viral RNA genome.
- Proteolytic processing of the precursors polyproteins by viral protease and maturation of the virions.
- ssRNA is copied into a linear dsDNA molecule by the reverse transcriptase.
- Nuclear entry of the viral dsDNA which is covalently and randomly integrated into the cell's genome by the viral integrase.