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The adenovirus E4‐ORF4 splicing enhancer protein interacts with a subset of phosphorylated SR proteins
Author(s) -
Nilsson Camilla Estmer,
PetersenMahrt Svend,
Durot Céline,
Shtrichman Ronit,
Krainer Adrian R.,
Kleinberger Tamar,
Akusjärvi Göran
Publication year - 2001
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/20.4.864
Subject(s) - rappaport , library science , medical school , medicine , philosophy , computer science , theology , medical education
SR proteins purified from uninfected HeLa cells inhibit adenovirus IIIa pre‐mRNA splicing by binding to the intronic IIIa repressor element (3RE). In contrast, SR proteins purified from late adenovirus‐infected cells are functionally inactivated as splicing repressor proteins by a virus‐induced dephosphorylation. We have shown that the adenovirus E4‐ORF4 protein, which binds the cellular protein phos phatase 2A (PP2A) and activates IIIa splicing in vitro and in vivo , induces SR protein dephosphorylation. Here we show that E4‐ORF4 interacts with only a subset of SR proteins present in HeLa cells. Thus, E4‐ORF4 interacts efficiently with SF2/ASF and SRp30c, but not with other SR proteins. Interestingly, E4‐ORF4 interacts with SF2/ASF through the latter's RNA recognition motifs. Furthermore, E4‐ORF4 interacts preferentially with the hyperphosphorylated form of SR proteins found in uninfected HeLa cells. E4‐ORF4 mutant proteins that fail to bind strongly to PP2A or SF2/ASF do not relieve the repressive effect of HeLa SR proteins on IIIa pre‐mRNA splicing in transient transfection experiments, suggesting that an interaction between all three proteins is required for E4‐ORF4‐induced SR protein dephosphorylation.