Recruitment of AtWHY1 and AtWHY3 by a distal element upstream of the kinesin gene AtKP1 to mediate transcriptional repression.

A 43-bp distal element, the AtKP1-related element (KPRE), was previously shown to repress the promoter activity of the kinesin gene AtKP1 in Arabidopsis thaliana. In order to identify KPRE-binding factor 1 (KBF1), a combination of ion-exchange chromatography, gel-filtration chromatography and DNA-affinity chromatography was used to purify KBF1 from whole cell extracts of Arabidopsis seedlings. Mass spectrometric identification showed that KBF1 contains two members of the whirly family of transcription factors, AtWHY1 and AtWHY3.