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Molecular and Cellular Biology, September 2009, p. 5020-5030, Vol. 29, No. 18
0270-7306/09/$08.00+0     doi:10.1128/MCB.00076-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Two GW Repeat Proteins Interact with Tetrahymena thermophila Argonaute and Promote Genome Rearrangement{triangledown} ,{dagger}

Janna Bednenko,1 Tomoko Noto,2 Leroi V. DeSouza,3,4 K. W. Michael Siu,3,4 Ronald E. Pearlman,4,5 Kazufumi Mochizuki,2 and Martin A. Gorovsky1*

Department of Biology, University of Rochester, Rochester, New York 14627,1 Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohr-Gasse 3, A-1030 Vienna, Austria,2 Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada,3 Center for Research in Mass Spectrometry, York University, Toronto, Ontario M3J 1P3, Canada,4 Department of Biology, York University, Toronto, Ontario M3J 1P3, Canada5

Received 16 January 2009/ Returned for modification 19 February 2009/ Accepted 21 June 2009

In conjugating Tetrahymena thermophila, massive DNA elimination occurs upon the development of the new somatic genome from the germ line genome. Small, ~28-nucleotide scan RNAs (scnRNAs) and Twi1p, an Argonaute family member, mediate H3K27me3 and H3K9me3 histone H3 modifications, which lead to heterochromatin formation and the excision of the heterochromatinized germ line-limited sequences. In our search for new factors involved in developmental DNA rearrangement, we identified two Twi1p-interacting proteins, Wag1p and CnjBp. Both proteins contain GW (glycine and tryptophan) repeats, which are characteristic of several Argonaute-interacting proteins in other organisms. Wag1p and CnjBp colocalize with Twi1p in the parental macronucleus early in conjugation and in the new developing macronucleus during later developmental stages. Around the time DNA elimination occurs, Wag1p forms multiple nuclear bodies in the developing macronuclei that do not colocalize with heterochromatic DNA elimination structures. Analyses of {Delta}WAG1, {Delta}CnjB, and double {Delta}WAG1 {Delta}CnjB knockout strains revealed that WAG1 and CnjB genes need to be deleted together to inhibit the downregulation of specific scnRNAs, the formation of DNA elimination structures, and DNA excision. Thus, Wag1p and CnjBp are two novel players with overlapping functions in RNA interference-mediated genome rearrangement in Tetrahymena.

* Corresponding author. Mailing address: Department of Biology, University of Rochester, Rochester, NY 14627. Phone: (585) 275-6988. Fax: (585) 275-2070. E-mail: goro{at}mail.rochester.edu

{triangledown} Published ahead of print on 13 July 2009.

{dagger} Supplemental material for this article may be found at http://mcb.asm.org/.

Molecular and Cellular Biology, September 2009, p. 5020-5030, Vol. 29, No. 18
0270-7306/09/$08.00+0     doi:10.1128/MCB.00076-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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