Recruitment of AtWHY1 and AtWHY3 by a distal element
upstream of the kinesin gene AtKP1 to mediate transcriptional
Ji-Yuan Xiong Æ Cheng-Xia Lai Æ Zhe Qu Æ
Xue-Yong Yang Æ Xing-Hua Qin Æ Guo-Qin Liu
Received: 26 February 2009 / Accepted: 22 July 2009 / Published online: 11 August 2009
Ó Springer Science+Business Media B.V. 2009
Abstract A 43-bp distal element, the AtKP1-related ele-
ment (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 tran-
scription factors, AtWHY1 and AtWHY3. KBF1 is a single
and double-stranded DNA-binding factor. A ChIP assay
showed that AtWHY1 and AtWHY3 bind to the upstream
region of AtKP1 gene in vivo. Over-expression of AtWHY1
and AtWHY3 led to an obvious decrease of AtKP1 tran-
scripts, based on quantitative real-time PCR analysis.
Interestingly, salicylic acid treatment resulted in an increase
of AtWHY1 and AtWHY3 transcripts, and a decrease of
AtKP1 transcripts. Thus, AtWHY1 and AtWHY3, as two
components of KBF1, can be recruited at the KPRE site to
mediate the transcriptional repression of AtKP1. Our results
prove that AtKP1 is a new downstream target of the whirly
family of transcription factors.
Keywords KPRE-binding factor 1 Á Whirly family
of transcription factors Á Transcriptional repression Á
Kinesin Á AtKP1-related element
Transcription factors play important roles in the activation
and repression of gene transcription by binding to the
regulatory regions of genes (Jones et al. 1988). The inter-
actions between transcription factors and promoters at the
DNA level are a decisive step in transcriptional regulation,
in which a multitude of DNA-protein and protein-protein
interactions activate or repress gene transcription by
forming functional and regulatory complexes (Suzuki et al.
1998). Transcription is a cumulative result of multiple
reactions and components, and the elucidation of critical
reactions such as DNA-protein interactions will increase
understanding of the whole process, and facilitate further
investigation of gene function.
Transcription factors are members of a superfamily that
performs different functions in the process of cell devel-
opment (Hori et al. 2003; Perez-Rodriguez et al. 2005),
differentiation (Reimold et al. 2001; Igarashi et al. 2007),
and signal transduction (Uno et al. 2000; Middleton et al.
2007), etc. The whirly family of transcription factors are
plant-speciﬁc proteins, and are predicted to have the ability
to bind to single-stranded DNA (Desveaux et al. 2005).
The ﬁrst identiﬁed member of the whirly proteins is PBF-2,
which activates potato PR-10a gene expression in an ERE
element-dependent manner. The cDNA for PBF-2 was
cloned and termed StWHY1, and demonstrated to play roles
in defense gene regulation (Desveaux et al. 2000, 2004).
Analysis of its crystal structure showed that four StWHY1
molecules associate with cyclic C4 symmetry, and the
Electronic supplementary material The online version of this
article (doi:10.1007/s11103-009-9533-7) contains supplementary
material, which is available to authorized users.
J.-Y. Xiong Á C.-X. Lai Á Z. Qu Á X.-Y. Yang Á X.-H. Qin Á
G.-Q. Liu (&)
State Key Laboratory of Plant Physiology and Biochemistry,
College of Biological Sciences, China Agricultural University,
100193 Beijing, China
Plant Mol Biol (2009) 71:437–449