A downstream regulatory element located within the coding sequence mediates autoregulated expression of the yeast fatty acid synthase gene FAS2 by the FAS1 gene product
P. Wenz et al., A downstream regulatory element located within the coding sequence mediates autoregulated expression of the yeast fatty acid synthase gene FAS2 by the FAS1 gene product, NUCL ACID R, 29(22), 2001, pp. 4625-4632
The fatty acid synthase genes FAS1 and FAS2 of the: yeast Saccharomyces cer
evisiae are transcriptionally, co-regulated by general transcription factor
s (such as: Reb1, Rap1 and Abf1) and by the phospholipid-specific heterodim
eric activator Ino2/Ino4, acting via their corresponding upstream binding s
ites. Here we: provide evidence for a positive autoregulatory influence of
FAS1 on FAS2 expression. Even with a constant FAS2 copy number, a 10-fold i
ncrease of FAS2 transcript amount was observed in the presence of FAS1 in m
ulti-copy, compared to a fas1 null mutant. Surprisingly, the first 66 nt of
the FAS2 coding region turned out as necessary and sufficient for FAS1-dep
endent gene expression. FAS2-lacZ fusion constructs deleted for this region
showed high reporters gene expression even in the absence of FAS1, arguing
for a negatively-acting downstream repression site (DRS) responsible for F
AS1-dependent expression of FAS2. Our data suggest that the FAS1 gene produ
ct, in addition to its catalytic function, is also required for the coordin
ate biosynthetic control of the yeast FAS complex. An excess of uncomplexed
Fas1 may be responsible for the deactivation of an FAS2-specific repressor
, acting via the DRS.