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

n1 -甲基- n3 -氨基羧基丙基假尿嘧啶是真核小核糖体亚基rRNA中最复杂的化学修饰。尿苷的生物合成需要三个步骤。由snR35引导的snoRNP催化尿嘧啶到伪尿嘧啶的修饰。我们之前已经证明spout类甲基转移酶Nep1引入了n1 -甲基。最近我们发现了将acp基团转化为n1 -甲基伪尿嘧啶的酶我们将其命名为Bam1。在这里，我们建议建立Bam1的acp转移酶活性的结构和功能基础，特别是了解允许Bam1利用SAM作为acp转移的底物而不是甲基供体的结构先决条件。此外，我们旨在了解该反应的催化机理。酵母中Bam1敲除和突变菌株的可用性将使我们能够研究这种化学复合物修饰的生理相关性及其在核糖体生物发生中的重要性。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疾病，类似于Nep1催化的n1甲基化所观察到的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.