Nucleic Acids Research Advance Access originally published online on November 29, 2007
Nucleic Acids Research 2008 36(2):532-538; doi:10.1093/nar/gkm1071
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Nucleic Acids Research, 2008, Vol. 36, No. 2 532-538
© 2007 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Molecular Biology |
The RNA-dependent RNA polymerase essential for post-transcriptional gene silencing in Neurospora crassa interacts with replication protein A
1Dipartimento di Biotecnologie Cellulari ed Ematologia, Università La Sapienza, Rome, Italy, 2European Brain Reaseach Institute, Fondazione Rita Levi-Montalcini, Rome, Italy and 3National Institute for Infectious Diseases L. Spallanzani, IRCCS, Rome, Italy
*To whom correspondence should be addressed. Tel/Fax: +39064457731; Email: carlo{at}bce.uniroma1.it The authors wish it to be known that, in their opinion, the first two authors should be regarded as joint First Authors.
Received October 2, 2007. Revised November 13, 2007. Accepted November 13, 2007.
Post-transcriptional gene silencing (PTGS) pathways play a role in genome defence and have been extensively studied, yet how repetitive elements in the genome are identified is still unclear. It has been suggested that they may produce aberrant transcripts (aRNA) that are converted by an RNA-dependent RNA polymerase (RdRP) into double-stranded RNA (dsRNA), the essential intermediate of PTGS. However, how RdRP enzymes recognize aberrant transcripts remains a key question. Here we show that in Neurospora crassa the RdRP QDE-1 interacts with Replication Protein A (RPA), part of the DNA replication machinery. We show that both QDE-1 and RPA are nuclear proteins and that QDE-1 is specifically recruited onto the repetitive transgenic loci. We speculate that this localization of QDE-1 could allow the in situ production of dsRNA using transgenic nascent transcripts as templates, as in other systems. Supporting a link between the two proteins, we found that the accumulation of short interfering RNAs (siRNAs), the hallmark of silencing, is dependent on an ongoing DNA synthesis. The interaction between QDE-1 and RPA is important since it should guide further studies aimed at understanding the specificity of the RdRP and it provides for the first time a potential link between a PTGS component and the DNA replication machinery.