El-Shami Mahmoud, Pontier Dominique, Lahmy Sylvie, Braun Laurence, Picart Claire, Vega Danielle, Hakimi Mohamed-Ali, Jacobsen Steven E, Cooke Richard, Lagrange Thierry
Laboratoire Génome et Développement de Plantes, Centre National de la Recherche Scientifique/Institut de Recherche pour le Développement/Université de Perpignan 5096, 66860 Perpignan Cedex, France.
Genes Dev. 2007 Oct 15;21(20):2539-44. doi: 10.1101/gad.451207.
Two forms of RNA Polymerase IV (PolIVa/PolIVb) have been implicated in RNA-directed DNA methylation (RdDM) in Arabidopsis. Prevailing models imply a distinct function for PolIVb by association of Argonaute4 (AGO4) with the C-terminal domain (CTD) of its largest subunit NRPD1b. Here we show that the extended CTD of NRPD1b-type proteins exhibits conserved Argonaute-binding capacity through a WG/GW-rich region that functionally distinguishes Pol IVb from Pol IVa, and that is essential for RdDM. Site-specific mutagenesis and domain-swapping experiments between AtNRPD1b and the human protein GW182 demonstrated that reiterated WG/GW motifs form evolutionarily and functionally conserved Argonaute-binding platforms in RNA interference (RNAi)-related components.
两种形式的RNA聚合酶IV(PolIVa/PolIVb)参与了拟南芥中的RNA指导的DNA甲基化(RdDM)过程。流行的模型认为,通过AGO4与最大亚基NRPD1b的C末端结构域(CTD)结合,PolIVb具有独特的功能。在这里,我们表明,NRPD1b型蛋白的扩展CTD通过富含WG/GW的区域表现出保守的AGO结合能力,该区域在功能上区分了Pol IVb和Pol IVa,并且对RdDM至关重要。AtNRPD1b与人类蛋白GW182之间的位点特异性诱变和结构域交换实验表明,重复的WG/GW基序在RNA干扰(RNAi)相关组分中形成了进化上和功能上保守的AGO结合平台。