6l8k
From Proteopedia
Structure of URT1 in complex with UTP
Structural highlights
Function[URT1_ARATH] UTP:RNA uridylyltransferase with a marked preference for uridine polymerization and a distributive activity for the first added nucleotides (PubMed:23748567, PubMed:25928405). Uridylates oligo(A)-tailed mRNAs to prevent 3' to 5' ribonucleotytic attacks (PubMed:23748567). Can prevent the 3' trimming of mRNAs still engaged on polysomes (PubMed:23748567). Acts synergistically with HESO1 in unmethylated miRNA uridylation, leading to their degradation (PubMed:25928341). URT1 and HESO1 prefer substrates with different 3' end nucleotides and act cooperatively to tail different forms of the same miRNAs (PubMed:25928405). URT1 and HESO1 act sequentially, with URT1 mono-uridylating the miRNAs followed by their further uridylation by HESO1 (PubMed:25928405). Has no effect on uridylation of heterochromatic siRNAs (PubMed:25928341). Able to act on AGO1-bound miRNAs and the uridylated species stay associated with AGO1 (PubMed:25928405).[1] [2] [3] Publication Abstract from PubMed3' uridylation is an essential modification associated with coding and noncoding RNA degradation in eukaryotes. In Arabidopsis, HESO1 was first identified as the major nucleotidyl transferase that uridylates most unmethylated miRNAs, and URT1 was later reported to play a redundant but important role in miRNA uridylation when HESO1 is absent. Two enzymes work sequentially and collaboratively to tail different forms of the same miRNAs in vivo. For mRNA, however, URT1 becomes the main enzyme to uridylate the majority of mRNA and repairs their deadenylated ends to restore the binding site for Poly(A) Binding Protein (PABP). HESO1, on the other hand, targets mostly the mRNAs with very short oligo(A) tails and fails in fulfilling the same task. To understand the structural basis these two functional homologues possess for their different substrate preferences and catalytic behaviors, we first determined the crystal structures of URT1 in the absence and presence of UTP. Our structures, together with functional assay and sequence analysis, indicated that URT1 has a conserved UTP-recognition mechanism analogue to the terminal uridylyl transferases from other species whereas HESO1 may evolve separately to recognize UTP in a different way. Moreover, URT1 N552 may be an important residue in interacting with 3' nucleotide of RNA substrate. The URT1 structure we determined represents the first structure of uridylyl transferase from plants, shedding light on the mechanisms of URT1/HESO1-dependent RNA metabolism. Crystal structure of Arabidopsis terminal uridylyl transferase URT1.,Zhu L, Hu Q, Cheng L, Jiang Y, Lv M, Liu Y, Li F, Shi Y, Gong Q Biochem Biophys Res Commun. 2020 Jan 30. pii: S0006-291X(20)30207-2. doi:, 10.1016/j.bbrc.2020.01.124. PMID:32008746[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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