It can act as a transcriptional repressor or activator and, when

binding at the initiator element, as a component of the basal

transcription complex. Binding sites for YY1 have been reported

in a wide variety of promoters and they exhibit substantial

diversity in their sequence. To better understand how YY1 interacts

with DNA and to be able to predict the presence of YY1 sites in

a more comprehensive fashion, we have selected YY1 binding sites

from a random pool of oligonucleotides. The sites display considerable

heterogeneity, but contain a conserved 5'-CAT-3' core flanked by

variable regions, generating the consensus

5'-(C/g/a)(G/t)(G/t/a)CATN(T/a)(T/g/c)-3', where the upper case

letters represent the preferred base. This high degree of flexibility

in DNA recognition can be predicted by modeling the interaction

of the four YY1 zinc fingers with DNA and a detailed model for

this interaction is presented and discussed.