Two consecutive zinc fingers in Sp1 and in MAZ are essential for interactions with cis-elements

The zinc finger proteins Sp1 and Myc-associated zinc finger protein (MAZ) a re transcription factors that control the expression of various genes. Regu lation of transcription by these factors is based on interactions between G C-rich DNA-binding sites (GGGCGG for Spl and GGGAGGG for MAZ) and the carbo xyl-terminal zinc finger motifs of the two proteins. Spl and MAZ have three and six zinc fingers, respectively, and the details of their interactions with cis-elements remain to be clarified. We demonstrate here that Sp1 and MAZ interact with the same GC-rich DNA-binding sites, apparently sharing DN A-binding sites with each other. We found that the DNA binding activities o f Spl and MAZ depended mainly on consecutive zinc fingers, namely the secon d and third zinc fingers in Spl and the third and fourth zinc fingers in MA Z. Furthermore, the interactions of the zinc finger proteins with the same cis-elements appear to play a critical role in the regulation of gene expre ssion. It seems plausible that two consecutive zinc finger motifs in a zinc finger protein might be essential for interaction of the protein with DNA.