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Nuclear localization is required for function of the essential clock protein FRQ
Author(s) -
Luo Chenghua,
Loros Jennifer J.,
Dunlap Jay C.
Publication year - 1998
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/17.5.1228
Subject(s) - biology , nuclear protein , microbiology and biotechnology , function (biology) , fungal protein , nuclear transport , computational biology , genetics , saccharomyces cerevisiae , cell nucleus , transcription factor , gene
The frequency ( frq ) gene in Neurospora encodes central components of a circadian oscillator, a negative feedback loop involving frq mRNA and two forms of FRQ protein. Here we report that FRQ is a nuclear protein and nuclear localization is essential for its function. Deletion of the nuclear localization signal (NLS) renders FRQ unable to enter into the nucleus and abolishes overt circadian rhythmicity, while reinsertion of the NLS at a novel site near the N‐terminus of FRQ restores its function. Each form of FRQ enters the nucleus soon after its synthesis in the early subjective day; there is no evidence for regulated sequestration in the cytoplasm prior to nuclear entry. The kinetics of the nuclear entry are consistent with previous data showing rapid depression of frq transcript levels following the synthesis of FRQ, and suggest that early in each circadian cycle, when FRQ is synthesized, it enters the nucleus and depresses the level of its own transcript.