Wrzesinski J, Bakin A, Ofengand J, Lane B G
Polish Academy of Sciences, Institute of Bioorganic Chemistry, Poznan.
IUBMB Life. 2000 Jul;50(1):33-7. doi: 10.1080/15216540050176566.
All nine pseudouridine (psi) residues in Escherichia coli 23S RNA are in or very near the peptidyl transfer centre (PTC) of the ribosome. Five psi synthases catalyze synthesis of these nine psi's. Deletion of the gene for one psi synthase, RluD, which directs synthesis of three closely clustered psi's in the decoding site of the PTC, has a profound negative impact on cell growth. We describe the isolation, without amplification from a cloned coding element, of the triple-site modifying enzyme, RluD, the N-terminal sequence of which has been used to clone and express the corresponding gene, rluD. Unlike "expressed" RluD, which so far has not been shown to modify one (1911) of the three closely clustered sites (1911, 1915, 1917), "natural" RluD modifies all three sites; and unlike another pai synthase, RluA, natural RluD has greatly expanded modifying activity at low Mg concentrations. These properties of the expressed and natural forms of RluD are discussed.
大肠杆菌23S RNA中的所有九个假尿苷（ψ）残基都位于核糖体的肽基转移中心（PTC）内或非常靠近该中心。五种ψ合成酶催化这九个ψ的合成。一种ψ合成酶RluD的基因缺失对细胞生长有深远的负面影响，RluD负责在PTC的解码位点指导三个紧密聚集的ψ的合成。我们描述了从克隆的编码元件中不经过扩增而分离出三位点修饰酶RluD的过程，其N端序列已用于克隆和表达相应的基因rluD。与迄今为止尚未显示能修饰三个紧密聚集位点（1911、1915、1917）之一（1911）的“表达型”RluD不同，“天然型”RluD能修饰所有三个位点；并且与另一种ψ合成酶RluA不同，天然RluD在低镁浓度下具有大大扩展的修饰活性。文中讨论了RluD表达型和天然型的这些特性。
