UAP56 associates with DRM2 and is localized to chromatin in Arabidopsis

Jacinthe Azevedo (1) , Claire Picart (1) , Laurent Dureau (1) , Dominique Pontier (2) , Sylvie Jaquinod-Kieffer (3) , Mohamed-Ali Hakimi (4, 5) , Thierry Lagrange (1)

1 LGDP - Laboratoire Génome et développement des plantes
2 Ecoépidémiologie évolutionniste
3 EDyP - Etude de la dynamique des protéomes
4 LAPM - Laboratoire Adaptation et pathogénie des micro-organismes [Grenoble]
5 IAB - Institute for Advanced Biosciences / Institut pour l'Avancée des Biosciences (Grenoble)

Repeated sequence expression and transposable element mobilization are tightly controlled by multilayer processes, which include DNA 5 0-cytosine methylation. The RNA-directed DNA methylation (RdDM) pathway, which uses siRNAs to guide sequence-specific directed DNA methylation, emerged specifically in plants. RdDM ensures DNA methylation maintenance on asymmetric CHH sites and specifically initiates de novo methyla-tion in all cytosine sequence contexts through the action of DRM DNA methyltransferases, of which DRM2 is the most prominent. The RdDM pathway has been well described, but how DRM2 is recruited onto DNA targets and associates with other RdDM factors remains unknown. To address these questions, we developed biochemical approaches to allow the identification of factors that may escape genetic screens, such as proteins encoded by multigenic families. Through both conventional and affinity purification of DRM2, we identified DEAD box RNA helicases U2AF56 Associated Protein 56 (UAP56a/b), which are widespread among eukary-otes, as new DRM2 partners. We have shown that, similar to DRM2 and other RdDM actors, UAP56 has chromatin-associated protein properties. We confirmed this association both in vitro and in vivo in reproductive tissues. In addition, our experiments also suggest that UAP56 may exhibit differential distribution in cells depending on plant organ. While originally identified for its role in splicing, our study suggests that UAP56 may also have other roles, and our findings allow us to initiate discussion about its potential role in the RdDM pathway. In plants, DNA methylation is maintained by a sophisticated network involving the cooperation of several specialized DNA methyltransferases targeting cytosines in specific sequence contexts [1]. Three distinct families of DNA methyltransferases cooperate to ensure cytosine methylation maintenance in plants. The first one is MET1, which is a conserved DNA methyltransferase homologous to mammalian DNMT1, which targets cytosines in a CG context [2]. Unlike their animal counterparts, plants also target methylation in a non-CG context. Thus, the chro-momethylases proteins, mainly CMT2 and CMT3, Abbreviations GST, glutathione-S-transferase; HRP, horseradish peroxidase; IP, immunoprecipitation; lncRNA, long non-coding RNA; MNase, micrococcal nuclease; RdDM, RNA-directed DNA methylation; UAP56a/b, U2AF56 Associated Protein 56. 1 FEBS Open Bio (

Mots clés: Arabidopsis; chromatin; DNA methylation; DRM2; RdDM; UAP56

Domaines: Sciences du Vivant [q-bio]; Biologie végétale; Biochimie, Biologie Moléculaire

Jacinthe Azevedo, Claire Picart, Laurent Dureau, Dominique Pontier, Sylvie Jaquinod-Kieffer, et al.. UAP56 associates with DRM2 and is localized to chromatin in Arabidopsis. FEBS Open Bio, 2019, 9 (5), pp.973-985. ⟨10.1002/2211-5463.12627⟩. ⟨hal-02326416⟩