Low molecular weight protein phosphatase APH mediates tyrosine dephosphorylation and ABA response in Arabidopsis.

Low molecular weight protein tyrosine phosphatase(LWM-PTP),also known as acid phosphatase,is a highly conserved tyrosine phosphatase in living organisms.However,the function of LWM-PTP homolog has not been reported yet in plants.Here,we revealed a homolog of acid phosphatase,APH,in Arabidopsis plants,is a functional protein tyrosine phosphatase.The aph mutants are hyposensitive to ABA in post-germination growth.We performed an anti-phosphotyrosine antibody-based quantitative phosphoproteomics in wild-type and aph mutant and identified hundreds of putative targets of APH,including multiple splicing factors and other transcriptional regulators.Consistently,RNA-seq analysis revealed that the expression of ABA-highly-responsive genes is suppressed in aph mutants.Thus,APH regulates the ABA-responsive gene expressions by regulating the tyrosine phosphorylation of multiple splicing factors and other post-transcriptional regulators.We also revealed that Tyr383 in RAF9,a member of B2 and B3 RAF kinases that phosphorylate and activate SnRK2s in the ABA signaling pathway,is a direct target site of APH.Phosphorylation of Tyr383 is essential for RAF9 activity.Our results uncovered a crucial function of APH in ABA-induced tyrosine phosphorylation in Arabidopsis.

驱动蛋白KIF4A染色体定位的调控机制

KIF4A是一类可以利用自身马达结构域水解ATP获取能量,并沿着微管向其正极末端方向移动的分子马达。因其在细胞分裂过程中与染色体结合,又称染色体驱动蛋白。KIF4A在细胞周期的不同时期都发挥重要作用。在有丝分裂间期,KIF4A与染色质结合,稳定染色质结构。在有丝分裂早期细胞中,KIF4A参与染色体的凝缩、中板集合及整列。至有丝分裂晚期,KIF4A参与中央纺锤体的形成,调控染色体的分离和胞质分裂的完成。KIF4A的细胞学作用决定于该分子马达在各个细胞结构的正确定位,因此KIF4A调控染色体的各种功能依赖于该分子马达在染色体的定位。目前研究显示,众多因素影响KIF4A在染色体的定位,该文通过综述已发表的控制KIF4A染色体定位的因素,阐述调控KIF4A在染色体定位的分子机制,为深入研究KIF4A调控染色体功能的机制提供新的思路。