Splicing of two weak 3' splice sites from the adenovirus major late region is enhanced in nuclear extracts from adenovirus infected cells.
The adenovirus major late transcription unit (MLTU) is an example of a complex alternatively spliced gene, in which more than 15 different 3' splice sites can be joined to a common 5' splice site. Maturation of the full repertoire of possible mRNAs requires late viral protein synthesis and occurs only at late stages of the infectious cycle (16-24 hpi). We are trying to decipher the mechanisms regulating alternative 3' splice site choice during the infectious cycle. Therefore, we examined the splicing activity of several 3' splice sites from the MLTU in vitro in nuclear extracts prepared from adenovirus infected cells (Ad NE) and from uninfected cells. The results suggest that pre-mRNAs with "weak" 3' splice sites (short, atypical polypyrimidine tracts) are activated and pre-mRNAs with long, prototypical polypyrimidine tracts are repressed in Ad NE. In fact, our data show a reciprocal correlation between the strength of a polypyrimidine tract, defined by its affinity for U2AF65K in vitro, and the efficiency of splicing in Ad NE. We are currently investigating the possible mechanisms responsible for this observed shift in 3' splice site choice during an adenovirus infection.
Mühlemann
O
O
Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institute, Stockholm, Sweden.
Kreivi
J P
JP
Akusjärvi
G
G
D000257:Adenoviridae Infections / Q000821:virology; D000260:Adenoviruses, Human / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D017398:Alternative Splicing; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002467:Cell Nucleus / Q000378:metabolism / Q000821:virology; D005814:Genes, Viral; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic
D012333:RNA, Messenger; D012367:RNA, Viral