ZINC-FINGERS-1-7 OF EVI1 FAIL TO BIND THE GATA MOTIF BY ITSELF BUT REQUIRE THE CORE SITE GACAAGATA FOR BINDING

EVI1 is a zinc finger oncoprotein that binds via fingers 1-7 to the se quence GACAAGATAA. The target genes on which EVI1 acts are unknown. Th is binding motif over laps with that for the GATA transcription factor s, (T/A)GATA(A/G), and GATA-1 can bind to and activate transcription v ia a GACAAGATAA motif. The possibility has been raised that, when over expressed in leukemogenesis, EVI1 may function by interfering with the differentiation-promoting action of GATA factors. To explore this, we have assessed the affinity of EVI1 for the GATA binding sites derived from erythroid-specific GATA-1 target genes, and found only low affin ity interactions. We examined the contacts between EVI1 and DNA by met hylation interference studies, which revealed extensive contacts betwe en EVI1 and its binding site. The importance of the contacts for high affinity binding was shown by in vitro quantitative gel shift studies and in vivo cotransfection studies. To examine what types of sequences from mouse genomic DNA bind to EVI1, we isolated and sequenced five E VI1-binding fragments, and each showed the GACAAGATA site. The data pr esented contribute to our knowledge of the binding specificity of EVI1 , and yield a clearer picture of what sequences can, and cannot, act a s targets for EVI1 action.