White Collar-1

It is a key component of a circadian molecular pathway that regulates many behavioral activities, including conidiation.

[5][6] WC-1 and WC-2, an interacting partner of WC-1, comprise the White Collar Complex (WCC) that is involved in the Neurospora circadian clock.

[8][9] The Neurospora circadian clock was discovered in 1959, when Pittendrigh et al. first described timing patterns in the asexual development of spores.

[3] Genetic screens of light-insensitive Neurospora mutant strains have repeatedly demonstrated abnormalities in the wc-1 gene.

[16] In functional Neurospora, the WC-1 LOV domain binds to the flavin adenine dinucleotide (FAD) chromophore,[3][18] which is responsible for the conversion of light to mechanical energy.

Light-induced responses are completely eliminated in WC-1 LOV knockout Neurospora mutants, although WC-1's transcription activation role persists in the dark.

[4] The White Collar Complex (WCC), the heterodimer of WC-1 and WC-2, acts as a positive element in the circadian clock.

[26] As part of the transcription-translation negative feedback-loop (TTFL), FRQ protein enters the nucleus and interacts with FRQ-interacting RNA Helicase (FRH) to promote the repression of WCC activity.

[28] FRQ has also been shown to interact with WC-2 in vitro, and a partial loss-of-function allele of wc-2 yields Neurospora with a long period length and altered temperature compensation, which is a key characteristic of circadian pacemakers.

Simplified Representation of Neurospora Circadian Clock. [ 6 ] WC-1 and WC-2 (WCC) act as positive activators of frq transcription. FRQ protein binds to an RNA helicase, FRH, and to CK1 forming a complex. [ 20 ] This complex interacts with WCC, promoting phosphorylation of WCC. Phosphorylation stabilizes WCC and promotes its export to the cytoplasm, effectively down-regulating frq transcription. [ 21 ]