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A gene encoding an RNase D exonuclease‐like protein is required for post‐transcriptional silencing in Arabidopsis
Author(s) -
Glazov Eugene,
Phillips Kenneth,
Budziszewski Gregory J.,
Meins Frederick,
Levin Joshua Z.
Publication year - 2003
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.2003.01810.x
Subject(s) - biology , arabidopsis , gene silencing , exoribonuclease , gene , rna interference , genetics , exonuclease , transposable element , microbiology and biotechnology , rnase p , rna , mutant , polymerase
Summary Post‐transcriptional gene silencing (PTGS) and the closely related phenomenon RNA interference (RNAi) result from the initial endonucleolytic cleavage of target mRNAs, which are then presumed to be completely hydrolyzed by exoribonucleases. To date, no plant genes required for PTGS are known to encode exoribonucleases. The Arabidopsis Werner Syndrome‐like exonuclease ( WEX ) gene encodes an RNase D domain most similar to that in human Werner Syndrome protein (WRN), but lacks the RecQ helicase domain. It is also related to Caenorhabditis elegans mut‐7 , which is essential for RNAi, PTGS, and transposon activity. We isolated a loss‐of‐function mutant, wex‐1 , that showed greatly reduced expression of WEX mRNA and early flowering. Although wex‐1 did not affect expression of a robust marker for transcriptional gene silencing (TGS), PTGS of a green‐fluorescent‐protein (GFP) reporter gene was blocked in wex‐1 and restored by ectopic expression of WEX, indicating that WEX is required for PTGS but not TGS. Thus, members of the RNase D protein family are required for PTGS in both plants and animals. Interestingly, WEX has been shown to interact with an Arabidopsis RecQ helicase, suggesting that these proteins might comprise a functional equivalent of WRN.