Putative metal finger structure of the human immunodeficiency virus type 1 enhancer binding protein HIV-EP1

The region containing two copies of the sequence GGGACTTTCC in the human immunodeficiency virus type 1 (HIV-1) long terminal repeat, that is an NF-kappa B binding site, functions as an enhancer element for HIV transcriptional regulation. By a Southwestern method we have isolated a cDNA encoding the HIV-1 enhancer binding protein (HIV-EP1) from a human B-cell lambda gt11 library. DNase I footprinting analysis using the HIV-EP1 protein expressed in Escherichia coli showed that HIV-EP1 specifically bound to the HIV-1 enhancer. HIV-EP1 protein contains a domain with two tandem "zinc finger" sequences initially described in the Xenopus transcription factor IIIA. This represents the first demonstration of the structural feature of the protein that binds to the HIV-1 enhancer.