Lsm proteins bind and stabilize RNAs containing 5 poly(A) tracts
Moraes, Karen C. M.
Anderson, John R.
Schneider, Robert J.
Wilusz, Carol J.
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Many orthopoxvirus messenger RNAs have an unusual nontemplated poly( A) tract of 5 to 40 residues at the 5 end. The precise function of this feature is unknown. Here we show that 5 poly( A) tracts are able to repress RNA decay by inhibiting 3 - to- 5 exonucleases as well as decapping of RNA substrates. UV cross- linking analysis demonstrated that the Lsm complex associates with the 5 poly( A) tract. Furthermore, recombinant Lsm1 - 7 complex specifically binds 5 poly( A) tracts 10 to 21 nucleotides in length, consistent with the length of 5 poly( A) required for stabilization. Knockdown of Lsm1 abrogates RNA stabilization by the 5 poly( A) tract. We propose that the Lsm complex simultaneously binds the 3 and 5 ends of these unusual messenger RNAs and thereby prevents 3 - to-5 decay. The implications of this phenomenon for cellular mRNA decay are discussed.
Извор:Nature Structural and Molecular Biology, 2007, 14, 9, 824-831
- NIGMS NIH HHS [GM72481]
ISSN: 1545-9985 (print)