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The Argonaute‐binding platform of NRPE 1 evolves through modulation of intrinsically disordered repeats
Author(s) -
Trujillo Joshua T.,
Beilstein Mark A.,
Mosher Rebecca A.
Publication year - 2016
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.14089
Subject(s) - argonaute , biology , gene silencing , computational biology , evolutionary biology , effector , genetics , binding site , conserved sequence , rna , rna interference , microbiology and biotechnology , dna , gene , base sequence
Summary Argonaute (Ago) proteins are important effectors in RNA silencing pathways, but they must interact with other machinery to trigger silencing. Ago hooks have emerged as a conserved motif responsible for interaction with Ago proteins, but little is known about the sequence surrounding Ago hooks that must restrict or enable interaction with specific Argonautes. Here we investigated the evolutionary dynamics of an Ago‐binding platform in NRPE 1, the largest subunit of RNA polymerase V. We compared NRPE 1 sequences from > 50 species, including dense sampling of two plant lineages. This study demonstrates that the Ago‐binding platform of NRPE 1 retains Ago hooks, intrinsic disorder, and repetitive character while being highly labile at the sequence level. We reveal that loss of sequence conservation is the result of relaxed selection and frequent expansions and contractions of tandem repeat arrays. These factors allow a complete restructuring of the Ago‐binding platform over 50–60 million yr. This evolutionary pattern is also detected in a second Ago‐binding platform, suggesting it is a general mechanism. The presence of labile repeat arrays in all analyzed NRPE 1 Ago‐binding platforms indicates that selection maintains repetitive character, potentially to retain the ability to rapidly restructure the Ago‐binding platform.