Fig. 7: A working model illustrating the role of TaHAKAI in WYMV replication.
From: An m6A methyltransferase confers host resistance by degrading viral proteins through ubiquitination
During WYMV infection, TaHAKAIR is phosphorylated by the host, whereas TaHAKAIS is not phosphorylated. TaHAKAIR and TaHAKAIS, which are m6A writers in plants, were used by WYMV to increase WYMV genomic m6A modifications and promote viral replication. The viral RNA-silenced suppressor P2 protein is subsequently translated from the viral genome and subsequently recognised by the E3 ligases TaHAKAIR and TaHAKAIS to perform ubiquitination functions to degrade the P2 protein. TaHAKAIS possesses weaker ubiquitination activity, leading to reduced P2 protein degradation, thus promoting viral replication. In contrast, phosphorylated TaHAKAIR has increased ubiquitination activity, leading to the degradation of most of the P2 protein and, therefore, the inhibition of WYMV infection. Moreover, TaHAKAIR also increases the m6A modification levels of TaWPS1 and reduces TaWPS1 mRNA stability, thereby increasing panicle length and spikelet number. The thicknesses of the solid blue and red arrows represent the strength of the function, and the dotted arrows represent unknown specific mechanisms.
