The Adenovirus L4-33K Protein: A Key Regulator of Virus-specific Alternative Splicing
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Adenoviruses have been extensively studied in the field of gene regulation, since their genes are subjected to a tightly controlled temporal expression during the virus lifetime. The early-to-late shift in adenoviral gene expression distinguishes two completely different programs in gene expression. The adenoviral L4-33K protein, which is the subject of this thesis, was previously implicated to be a key player in the transition from the early to the late phase of infection. Here we show that L4-33K activates late gene expression by functioning as a virus-encoded alternative RNA splicing factor activating splicing of transcripts containing weak 3’ splice sites; a feature common to the viral genes expressed at late times of infection.
The splicing enhancer activity of L4-33K was mapped to a tiny arginine/serine (RS) repeat in the carboxyl-terminal domain of the protein. Also, the subcellular distribution to the nucleus with enrichment in the nuclear membrane and subnuclear redistribution to viral replication centers during a lytic infection was observed to depend on this motif. RS repeats are common features for the cellular splicing factors serine/arginine-rich (SR) proteins, which in turn are regulated by reversible phosphorylation.
We further show that L4-33K is phosphorylated by two cellular protein kinases, the double-stranded DNA-dependent protein kinase (DNA-PK) and protein kinase A (PKA) in vitro. Interestingly, DNA-PK and PKA have opposite effects on the control of the temporally regulated L1 alternative RNA splicing. DNA-PK functions as an inhibitor of the late specific L1-IIIa pre-mRNA splicing whereas PKA functions as an activator of L1-IIIa pre-mRNA splicing.
In summary, this thesis describes L4-33K as an SR protein related viral alternative splicing factor. A tiny RS repeat conveys splicing enhancer activity as well as redistribution of L4-33K to replication centers. Finally, DNA-PK and PKA that phosphorylates L4-33K are suggested to be novel regulatory factors controlling adenovirus alternative splicing.
Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2011. , 66 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 709
L4-33K, adenovirus, splicing, phosphorylation, localization, replication centers, L4-22K, MLTU, DNA-PK, DNA-dependent protein kinase, PKA, cAMP-dependent protein kinase, transcription sites, SR protein
Microbiology in the medical area
Research subject Medical Virology
IdentifiersURN: urn:nbn:se:uu:diva-159632ISBN: 978-91-554-8178-0OAI: oai:DiVA.org:uu-159632DiVA: diva2:445961
2011-11-17, C10:301, BMC, Husargatan 3, Uppsala, 09:15 (English)
Öhman, Marie, professor
Akusjärvi, Göran, professorSchwartz, Stefan, professor
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