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BMC Biol August 3, 2009; 7 45.

TBP2 is a substitute for TBP in Xenopus oocyte transcription.

Akhtar W , Veenstra GJ .

BACKGROUND: TATA-box-binding protein 2 (TBP2/TRF3) is a vertebrate-specific paralog of TBP that shares with TBP a highly conserved carboxy-terminal domain and the ability to bind the TATA box. TBP2 is highly expressed in oocytes whereas TBP is more abundant in embryos. RESULTS: We find that TBP2 is proteolytically degraded upon meiotic maturation; after germinal vesicle breakdown relatively low levels of TBP2 expression persist. Furthermore, TBP2 localizes to the transcriptionally active loops of lampbrush chromosomes and is recruited to a number of injected promoters in oocyte nuclei. Using an altered binding specificity mutant reporter system we show that TBP2 promotes RNA polymerase II transcription in vivo. Intriguingly, TBP, which in oocytes is undetectable at the protein level, can functionally replace TBP2 when ectopically expressed in oocytes, showing that switching of initiation factors can be driven by changes in their expression. Proteolytic degradation of TBP2 is not required for repression of transcription during meiotic maturation, suggesting a redundant role in this repression or a role in initiation factor switching between oocytes and embryos. CONCLUSION: The expression and transcriptional activity of TBP2 in oocytes show that TBP2 is the predominant initiation factor in oocytes, which is substituted by TBP on a subset of promoters in embryos as a result of proteolytic degradation of TBP2 during meiotic maturation.

PubMed ID: 19650908
PMC ID: PMC2731028
Article link: BMC Biol

Species referenced: Xenopus laevis
Genes referenced: cat.2 ccn1 ctrl gtf2f2 hsp70 hspa1l mapk1 tbp tbpl2 zfp36l2
Antibodies: Mos Ab2

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References [+] :
Bush, Variations in intracellular levels of TATA binding protein can affect specific genes by different mechanisms. 2007, Pubmed