S. Bartoszewski et Jb. Gibson, Regulation of the expression of the sn-glycerol-3-phosphate dehydrogenase gene in Drosophila melanogaster, BIOCHEM GEN, 36(9-10), 1998, pp. 329-350
P element-mediated transformation has been used to investigate the regulati
on of expression of the sn-glycerol-3-phosphate dehydrogenase gene of Droso
phila melanogaster. A 13-kb construct containing the eight exons and associ
ated introns, 5 kb of the 5' region, and 3 kb downstream from the structura
l gene produced normal levels of enzyme activity and rescued the poor viabi
lity of flies lacking the enzyme. Ail the regulatory elements essential for
normal enzyme expression were located in a fragment that included the exon
s and introns and 1-kb upstream noncoding sequence. Deletions of the 1.6-kb
second intron reduced activity to 25%. Transformants with fusion construct
s between the sn-glycerol-3- phosphate dehydrogenase gene and the P-galacto
sidase gene from E. coli revealed three elements that affected expression.
A (CT)(9) repeat element at the 5' end of the second intron increased expre
ssion in both larvae and adults, particularly at emergence. A second regula
tory element, which includes a (CT)(7) repeat, was located 5' to the TATA b
ox and had similar effects on the gene's expression. A third undefined, enh
ancer was located in rite second intron, between 0.5 and 1.8 kb downstream
of the translation initiation codon. This element increases enzyme activity
to a similar extent in larvae and adults but has little effect when the en
hancer at the 5' end of the intron is present.