THE PLANT CELL, Vol 9, Issue 10 1791-1803, Copyright © 1997 by American Society of Plant Biologists
Effect of the Nuclear Factors EmBP1 and Viviparous1 on the Transcription of the Em Gene in HeLa Nuclear Extracts
M. A. Razik and R. S. Quatrano
Department of Biology and Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3280
Templates constructed from the wheat Em and maize rab28 promoters are
efficiently and accurately transcribed in the well-characterized cell-free
transcription system prepared from HeLa nuclei. Deletion analysis of the Em
promoter indicates that a G-box (CACGTG) element (Em1b) is required for
transcription. USF, a Myc transcription factor in HeLa nuclear extracts,
activates transcription by binding to Em1b, as shown by the ability of an
antibody raised against USF to inhibit transcription and to interfere with
Em1b complex formation in an electrophoretic mobility shift assay. The
addition of the recombinant Viviparous1 protein from maize to HeLa nuclear
extracts specifically stimulated transcription of the Em promoter but was
dependent on the presence of USF in the extract. In USF-depleted extracts,
the addition of recombinant EmBP1, a basic leucine zipper transcription
factor from wheat, activated transcription through Em1b as well as from a
similar G-box in the adenovirus major late promoter. Our study demonstrates
that the basic transcriptional apparatus in HeLa nuclear extract supports
transcription from plant promoters and can be used to assay the function of
certain plant nuclear proteins, thereby helping to determine their effects
on transcription.
