Foamy virus reverse transcriptase is expressed independently from the Gag protein.
AUTOR(ES)
Enssle, J
RESUMO
In the foamy virus (FV) subgroup of retroviruses the pol genes are located in the +1 reading frame relative to the gag genes and possess potential ATG initiation codons in their 5' regions. This genome organization suggests either a + 1 ribosomal frameshift to generate a Gag-Pol fusion protein, similar to all other retroviruses studied so far, or new initiation of Pol translation, as used by pararetroviruses, to express the Pol protein. By using a genetic approach we have ruled out the former possibility and provide evidence for the latter. Two down-mutations (M53 and M54) of the pol ATG codon were found to abolish replication and Pol protein expression of the human FV isolate. The introduction of a new ATG in mutation M55, 3' to the down-mutated ATG of mutation M53, restored replication competence, indicating that the pol ATG functions as a translational initiation codon. Two nonsense mutants (M56 and M57), which functionally separated gag and pol with respect to potential frame-shifting sites, were also replication-competent, providing further genetic evidence that FVs express the Pol protein independently from Gag. Our results show that during a particular step of the replication cycle, FVs differ fundamentally from all other retroviruses.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=39500Documentos Relacionados
- Nuclear localization of foamy virus Gag precursor protein.
- The human foamy virus pol gene is expressed as a Pro-Pol polyprotein and not as a Gag-Pol fusion protein.
- Reverse transcriptase from simian foamy virus serotype 1: purification and characterization.
- Transcomplementation of nucleotide priming and reverse transcription between independently expressed TP and RT domains of the hepatitis B virus reverse transcriptase.
- Reverse transcriptase and protease activities of avian leukosis virus Gag-Pol fusion proteins expressed in insect cells.