Mizutani Kenji, Machida Yoshitaka, Unzai Satoru, Park Sam-Yong, Tame Jeremy R H
Protein Design Laboratory, Yokohama City University, Suehiro 1-7-29, Tsurumi, Yokohama 230-0045, Japan.
Biochemistry. 2004 Apr 20;43(15):4454-63. doi: 10.1021/bi036079c.
The most frequent modification of RNA, the conversion of uridine bases to pseudouridines, is found in all living organisms and often in highly conserved locations in ribosomal and transfer RNA. RluC and RluD are homologous enzymes which each convert three specific uridine bases in Escherichia coli ribosomal 23S RNA to pseudouridine: bases 955, 2504, and 2580 in the case of RluC and 1911, 1915, and 1917 in the case of RluD. Both have an N-terminal S4 RNA binding domain. While the loss of RluC has little phenotypic effect, loss of RluD results in a much reduced growth rate. We have determined the crystal structures of the catalytic domain of RluC, and full-length RluD. The S4 domain of RluD appears to be highly flexible or unfolded and is completely invisible in the electron density map. Despite the conserved topology shared by the two proteins, the surface shape and charge distribution are very different. The models suggest significant differences in substrate binding by different pseudouridine synthases.
RNA最常见的修饰，即尿苷碱基向假尿苷的转化，存在于所有生物体中，且常见于核糖体RNA和转运RNA的高度保守位置。RluC和RluD是同源酶，它们分别将大肠杆菌核糖体23S RNA中的三个特定尿苷碱基转化为假尿苷：RluC作用于碱基955、2504和2580，RluD作用于碱基1911、1915和1917。两者都有一个N端S4 RNA结合结构域。虽然RluC的缺失对表型影响很小，但RluD的缺失会导致生长速率大幅降低。我们已经确定了RluC催化结构域和全长RluD的晶体结构。RluD的S4结构域似乎高度灵活或未折叠，在电子密度图中完全不可见。尽管这两种蛋白质具有相同的保守拓扑结构，但表面形状和电荷分布却非常不同。这些模型表明，不同的假尿苷合酶在底物结合方面存在显著差异。
