@misc{oai:ir.soken.ac.jp:00000895,
author = {李, 豊倩 and リ, ホウセイ and LI, Feng-Qian},
month = {2016-02-17, 2016-02-17},
note = {FTZ-FI has been identified as a sequence specific DNA-binding
protein in Drosophila. It binds to a 9 base pairs sequence in the upstream
regulatory region of the fushi tarazu (ftz) gene. Binding site-dependent
expression of the ftz-lacZ fusion genes in transformed embryos showed
that FTZ-F1 is a positive regulator of the ftz gene. A posterior silk gland
extract from the silkworm Bombyx mori contains a factor termed
BmFTZ-F1 which recognizes the same DNA sequence as FTZ-F1 and
has many biochemical characters similar to FTZ-F1. Molecular cloning
of cDNAs for FTZ-F1 and BmFTZ-F1 revealed that they are members of
the steroid hormone receptor superfamily and share homologies in the
DNA-binding and the putative ligand-binding domains.
Using the in vitro transcription systems from posterior silk gland
cells, I found that BmFTZ-F1 can activate transcription of the ftz gene
in a FTZ-F1-binding site dependent manner. To elucidate the mechanism
of transactivation by BmFTZ-F1, I used in vitro transcription systems
from HeLa cells. Because the HeLa system does not contain a FTZ-F1 like
activity, it serves as a recipient in complementation assay for active
components derived from the posterior silk gland extract. The results of
these analyses suggest that two proteins (18kDa and 22kDa polypeptides)
termed MBF (mediator of BmFTZ-F1) 1 and MBF2, respectively, that
form a heterodimer and mediate activiation of in vitro transcription
from the ftz gene promotor by BmFTZ-F1. Neither MBF1 nor MBF2
binds to DNA. MBF1 interacts with BmFTZ-F1 and stabilizes the
BmFTZ-F1･DNA complex. MBF1 also makes a direct contact with
TATA-binding protein (TBP). Both MBF1 and MBF2 are necessary to
form a complex between BmFTZ-F1 and TBP. I propose a model in
which MBF1 and MBF2 form a bridge between BmFTZ-F1 and TBP,
and mediate transactivation by stabilizing the protein･DNA interactions.
This is the first isolation of mediators capable of modulating transactivator
function directly., application/pdf, 総研大甲第89号},
title = {Mediators for Activation of fushi tarazu Gene Transcription by BmFTZ-F1},
year = {}
}