Aub and Ago3 Are Recruited to Nuage through Two Mechanisms to Form a Ping-Pong Complex Assembled by Krimper
In Drosophila, two Piwi proteins, Aubergine (Aub) and Argonaute-3 (Ago3), localize to perinuclear "nuage" granules and use guide piRNAs to target and destroy transposable element transcripts. We find that Aub and Ago3 are recruited to nuage by two different mechanisms. Aub requires a piRNA guide for nuage recruitment, indicating that its localization depends on recognition of RNA targets. Ago3 is recruited to nuage independently of a piRNA cargo and relies on interaction with Krimper, a stable component of nuage that is able to aggregate in the absence of other nuage proteins. We show that Krimper interacts directly with Aub and Ago3 to coordinate the assembly of the ping-pong piRNA processing (4P) complex. Symmetrical dimethylated arginines are required for Aub to interact with Krimper, but they are dispensable for Ago3 to bind Krimper. Our study reveals a multi-step process responsible for the assembly and function of nuage complexes in piRNA-guided transposon repression.
© 2015 Elsevier Inc. Received: March 23, 2015; Revised: June 26, 2015; Accepted: July 20, 2015; Published: August 20, 2015. We thank Katalin Fejes Toth and members of the Aravin and Fejes Toth labs for discussion and critical review of this manuscript. The authors would like to thank Andres Collazo and the Beckman Imaging Facility at the California Institute of Technology and Peter Rapp for assistance in developing our FRAP protocol, Georgi Marinov for assistance with piRNA analysis, and Igor Antoshechkin of the Millard and Muriel Jacobs Genetics and Genomics Laboratory. We are grateful to Julius Brennecke, Phillip Zamore, Zhao Zhang, and Toshie Kai, for fly stocks and other reagents. This work was supported by grants from the National Institutes of Health (R01 GM097363 and DP2 OD007371A) and by the Searle Scholar and the Packard Fellowship Awards to A.A.A.
Supplemental Material - mmc1.pdf
Accepted Version - nihms710553.pdf