E. Chernokalskaya et al., CLEAVAGE PROPERTIES OF AN ESTROGEN-REGULATED POLYSOMAL RIBONUCLEASE INVOLVED IN THE DESTABILIZATION OF ALBUMIN MESSENGER-RNA, Nucleic acids research, 25(4), 1997, pp. 735-742
Previous work from this laboratory [Dompenciel, R.E., Garnepudi, V.R.
and Schoenberg, D.R. (1995) J. Biol. Chem. 270, 610-6118] described th
e purification and properties of an estrogen-regulated endonuclease is
olated from Xenopus liver polysomes that is involved in the destabiliz
ation of albumin mRNA. The present study mapped cleavages made by this
enzyme onto the secondary structure of the portion of albumin mRNA be
aring the major cleavage sites, The predominant cleavages occur in the
overlapping APyrUGA sequence AUUGACUGA present in a single-stranded l
oop region, and in AUUGA located within a bulged AU-rich stem, A struc
tural mutation which converted the major loop cleavage site to a hairp
in bearing one APyrUGA element eliminated cleavage at the intact site.
This confirms that the polysomal RNase is specific for single-strande
d RNA. Additional point mutations in the major loop characterized the
nucleoside sequence requirements for cleavage, Finally, snake venom ex
onuclease was used to demonstrate the polysomal RNase generates produc
ts with a 3' hydroxyl. Binding of an estrogen-induced protein to a por
tion of the 3' UTR of vitellogenin mRNA may be involved in its stabili
zation by estrogen [Dodson, R.E. and Shapiro, D.J. (1994) Mel. Cell. B
iol. 14, 3130-3138]. The core binding;site for this protein bears the
sequence APyrUGA, suggesting that stabilization maybe accomplished by
occlusion of a cleavage site for the polysomal RNase.