Loading…
The mechanism and regulation of deadenylation: Identification and characterization of Xenopus PARN
In Xenopus oocytes, the deadenylation of a specific class of maternal mRNAs results in their translational repression. Here we report the purification, characterization, and molecular cloning of the Xenopus poly(A) ribonuclease (xPARN). xPARN copurifies with two polypeptides of 62 kDa and 74 kDa, an...
Saved in:
Published in: | RNA (Cambridge) 2001-06, Vol.7 (6), p.875-886, Article S1355838201010020 |
---|---|
Main Authors: | , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that cite this one |
Online Access: | Get full text |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Summary: | In Xenopus oocytes, the deadenylation of a specific
class of maternal mRNAs results in their translational
repression. Here we report the purification, characterization,
and molecular cloning of the Xenopus poly(A) ribonuclease
(xPARN). xPARN copurifies with two polypeptides of 62 kDa
and 74 kDa, and we provide evidence that the 62-kDa protein
is a proteolytic product of the 74-kDa protein. We have
isolated the full-length xPARN cDNA, which contains the
tripartite exonuclease domain conserved among RNase D family
members, a putative RNA recognition motif, and a domain
found in minichromosome maintenance proteins. Characterization
of the xPARN enzyme shows that it is a poly(A)-specific
3′ exonuclease but does not require an A residue
at the 3′ end. However, the addition of 25 nonadenylate
residues at the 3′ terminus, or a 3′ terminal
phosphate is inhibitory. Western analysis shows that xPARN
is expressed throughout early development, suggesting that
it may participate in the translational silencing and destabilization
of maternal mRNAs during both oocyte maturation and embryogenesis.
In addition, microinjection experiments demonstrate that
xPARN can be activated in the oocyte nucleus in the absence
of cytoplasmic components and that nuclear export of deadenylated
RNA is impeded. Based on the poly(A) binding activity of
xPARN in the absence of catalysis, a model for substrate
specificity is proposed. |
---|---|
ISSN: | 1355-8382 1469-9001 |
DOI: | 10.1017/S1355838201010020 |