Functional and Structural Analysis of the 18S rRNA aminocarboxypropyl transferase Bam1

N1-甲基-N3-氨基羧基丙基-假尿苷是真核生物核糖体小亚基rRNA中化学上最复杂的修饰。它的生物合成从尿苷需要三个步骤。尿苷至假尿苷的修饰由snR 35引导的snoRNP催化。我们以前表明，SPOUT类甲基转移酶Nep 1引入N1-甲基。最近，我们鉴定了将acp基团转移到N1-甲基假尿苷的酶，我们将其命名为Bam 1。在这里，我们建议建立的ACP转移酶活性的Bam 1的结构和功能的基础，特别是要了解的结构的先决条件，使Bam 1利用SAM作为ACP转移的底物，而不是作为一个甲基基团的供体。此外，我们的目的是了解该反应的催化机理。在酵母中Bam 1的敲除和突变株的可用性将使我们能够研究这种化学复杂修饰的生理相关性及其在核糖体生物合成中的重要性。由于强烈的人类同源性，我们的研究也可能揭示新的核糖体病，类似于观察到的Nep 1催化的N1-甲基化的Bowen-Conradi综合征。

N1-methyl-N3-aminocarboxypropyl-pseudouridine is the chemically most complex modification occurring in eukaryotic small ribosomal subunit rRNA. Its biosynthesis from uridine requires three steps. The uridine to pseudouridine modification is catalyzed by a snoRNP guided by snR35. We previously showed that the SPOUT-class methyltransferase Nep1 introduces the N1-methyl group. Very recently we identified the enzyme that transfers the acp group to the N1-methylpseudouridine which we named Bam1. Here we propose to establish the structural and functional basis for the acp transferase activity of Bam1 and in particular to understand the structural prerequisites that allow Bam1 to utilize SAM as a substrate for acp transfer instead as a methyl group donor. Furthermore, we aim at understanding the catalytic mechanism of this reaction. The availability of knock-out and mutant strains for Bam1 in yeast will allow us to investigate the physiological relevance of this chemically complex modification and its importance in ribosome biogenesis. Due to the strong human homologies, our investigation could possibly also unravel new ribosomopathies, similar to the Bowen-Conradi syndrome observed for Nep1 catalysed N1-methylation.