Center for Structural Molecular Biology, Brazilian Synchrotron Light Laboratory, LNLS Rua Giuseppe Maximo Scolfaro 10000, PO Box 6192, CEP 13083-970 Campinas, SP, Brazil.
J Mol Biol. 2010 Mar 5;396(4):1053-69. doi: 10.1016/j.jmb.2009.12.039. Epub 2010 Jan 4.
Shwachman-Bodian-Diamond syndrome is an autosomal recessive genetic syndrome with pleiotropic phenotypes, including pancreatic deficiencies, bone marrow dysfunctions with increased risk of myelodysplasia or leukemia, and skeletal abnormalities. This syndrome has been associated with mutations in the SBDS gene, which encodes a conserved protein showing orthologs in Archaea and eukaryotes. The Shwachman-Bodian-Diamond syndrome pleiotropic phenotypes may be an indication of different cell type requirements for a fully functional SBDS protein. RNA-binding activity has been predicted for archaeal and yeast SBDS orthologs, with the latter also being implicated in ribosome biogenesis. However, full-length SBDS orthologs function in a species-specific manner, indicating that the knowledge obtained from model systems may be of limited use in understanding major unresolved issues regarding SBDS function, namely, the effect of mutations in human SBDS on its biochemical function and the specificity of RNA interaction. We determined the solution structure and backbone dynamics of the human SBDS protein and describe its RNA binding site using NMR spectroscopy. Similarly to the crystal structures of Archaea, the overall structure of human SBDS comprises three well-folded domains. However, significant conformational exchange was observed in NMR dynamics experiments for the flexible linker between the N-terminal domain and the central domain, and these experiments also reflect the relative motions of the domains. RNA titrations monitored by heteronuclear correlation experiments and chemical shift mapping analysis identified a classic RNA binding site at the N-terminal FYSH (fungal, Yhr087wp, Shwachman) domain that concentrates most of the mutations described for the human SBDS.
Shwachman-Bodian-Diamond 综合征是一种常染色体隐性遗传综合征，具有多种表型，包括胰腺功能不全、骨髓功能障碍伴骨髓增生异常或白血病风险增加，以及骨骼异常。该综合征与 SBDS 基因突变有关，该基因编码一种保守蛋白，在古菌和真核生物中具有同源物。Shwachman-Bodian-Diamond 综合征的多种表型可能表明，一种功能齐全的 SBDS 蛋白需要不同的细胞类型。已有研究预测了古菌和酵母 SBDS 同源物具有 RNA 结合活性，而后者也与核糖体生物发生有关。然而，全长 SBDS 同源物在物种特异性方式下发挥作用，这表明从模型系统获得的知识可能在理解 SBDS 功能的主要未解决问题方面具有有限的用途，即人类 SBDS 突变对其生化功能的影响及其 RNA 相互作用的特异性。我们使用 NMR 光谱法确定了人 SBDS 蛋白的溶液结构和骨架动力学，并描述了其 RNA 结合位点。与古菌晶体结构类似，人 SBDS 的整体结构由三个折叠良好的结构域组成。然而，在 NMR 动力学实验中，在 N 端结构域和中心结构域之间的柔性接头中观察到明显的构象交换，这些实验还反映了结构域的相对运动。异核相关实验和化学位移映射分析监测的 RNA 滴定确定了位于 N 端 FYSH（真菌、Yhr087wp、Shwachman）结构域的经典 RNA 结合位点，该位点集中了大多数描述的人类 SBDS 突变。
