White Collar-1, a DNA Binding Transcription Factor and a Light Sensor
Qiyang He,1*
Ping Cheng,1*
Yuhong Yang,1
Lixing Wang,1
Kevin H. Gardner,2
Yi Liu1
Blue light regulates many physiological processes in
fungi, but their photoreceptors are not known. In Neurospora
crassa, all light responses depend on the Per-Arnt-Sim (PAS)
domain-containing transcription factor white
collar-1 (wc-1). By removing the WC-1 light, oxygen,
or voltage domain, a specialized PAS domain that binds flavin
mononucleotide in plant phototropins, we show that light responses are
abolished, including light entrainment of the circadian clock. However,
the WC-1-mediated dark activation of frq remains normal in
this mutant, and the circadian clock can be entrained by temperature.
Furthermore, we demonstrate that the purified Neurospora
WC-1-WC-2 protein complex is associated with stoichiometric
amounts of the chromophore flavin-adenine dinucleotide. Together, these
observations suggest that WC-1 is the blue-light photoreceptor for the
circadian clock and other light responses in Neurospora.
1 Department of Physiology,
2 Department of Biochemistry, University of Texas
Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX
75390, USA.
*
These authors contributed equally to this work.
To whom correspondence should be addressed. E-mail:
Yi.Liu{at}UTsouthwestern.edu
