TITLE:
Identification of the constitutive ultradian oscillator of the circadian clock (ENOX1) in Saccharomyces cerevisiae
AUTHORS:
Sara S. Dick, Aya Ryuzoji, Dorothy M. Morré, D. James Morré
KEYWORDS:
Biological Clock; ECTO-NOX (ENOX) Proteins; Ultradian Oscillator; Yeast (Saccharomyces cerevisiae)
JOURNAL NAME:
Advances in Biological Chemistry,
Vol.3 No.3,
June
25,
2013
ABSTRACT: A yeast (Saccharomyces
cerevisiae) deletion library was screened based on NADH fluorescence using
a 384 well plate assay and robotics to identify a yeast isolate lacking the 24
min periodic cell surface oxidase. The oxidase was shown previously to be a
candidate ultradian oscillator of the yeast’s biological clock. The cDNA
was cloned from a yeast overexpression library and the encoded protein was expressed in bacteria and characterized. Glyceraldehyde-3-phosphate
dehydrogenase activity was used as the cellular circadian indicator. The
identified gene was YML117W which encodes a ca 126 kDa putative RNA-binding
protein. The candidate ENOX1 activity from yeast had functional characteristics
similar to those of other constitutive ENOX1 proteins of eukaryotes
exhibiting oscillating activities with a temperature independent period
length of 24 min phased by melatonin and low frequency electromagnetic fields
and susceptible to inhibition by the ENOX1 inhibitor, simalikalactone D. The
YML117W deletion mutant cells lacked the ENOX1 clock output present in wild
type yeast. The findings identify YML117W as the ENOX1 of Saccharomyces cerevisiae and support its proposed function as an
ultradian oscillator of the yeast biological clock.