Analysis of chimeric ribosomal stalk complexes from eukaryotic and bacterial sources: structural features responsible for specificity of translation factors
Analysis of chimeric ribosomal stalk complexes from eukaryotic and bacterial sources: structural features responsible for specificity of translation factors
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DOI：
10.1111/j.1365-2443.2012.01586.x
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发表时间：
2012-04-01
期刊：
影响因子：
2.1
通讯作者：
Uchiumi, Toshio
中科院分区：
文献类型：
--
作者：
Mochizuki, Masahiro;Kitamyo, Masumi;Uchiumi, Toshio
核糖体蛋白P0与柔性柄蛋白P1中心点P2的两个异二聚体形成五聚体复合物，并在真核核糖体与翻译因子的功能相互作用中起作用。为了研究真核生物特有的P0结构域的功能，我们构建了家蚕P0和大肠杆菌对应物L10之间的各种嵌合体。用P0的C-末端区域替换L10的C-末端区域允许两个P1中心点P2异二聚体的结合，这支持依赖于真核延伸因子eEF-2/eEF-1a的核糖体活性，但不支持依赖于细菌因子EF-G/EF-Tu的活性。相反，用L10的C-末端区域替换P0允许两个细菌L12同源二聚体的结合，这导致依赖于细菌因子的低水平活性。插入的延伸区域的P0是不存在的细菌对应到L10不影响L12的结合或细菌因子依赖的活性，但删除该区域从P0导致真核细胞因子依赖的活性降低40%。结果表明，P0和L10的C-末端区域负责同源茎二聚体和翻译因子的核糖体特异性的结合，并建议扩展区域仅参与真核生物因子的可访问性。
Ribosomal protein P0 forms a pentameric complex with two heterodimers of the flexible stalk proteins P1 center dot P2 and plays a role in the functional interaction of eukaryotic ribosomes with translational factors. To investigate the functionality of domains of P0 characteristic to eukaryotes, we constructed various chimeras between silkworm P0 and Escherichia coli counterpart L10. Replacement of the C-terminal region of L10 with that of P0 allowed the binding of two P1 center dot P2 heterodimers, which supported ribosomal activity dependent on eukaryotic elongation factors eEF-2/eEF-1a, but not activity dependent on bacterial factors EF-G/EF-Tu. Conversely, replacement of the C-terminal region of P0 with that of L10 allowed binding of two bacterial L12 homodimers, which resulted in a low level of activity dependent on bacterial factors. Insertion of the extended region of P0 that is absent in the bacterial counterpart into L10 did not affect L12 binding or bacterial factor-dependent activity, but deletion of this region from P0 resulted in a 40% reduction in eukaryotic factor-dependent activity. The results indicate that the C-terminal regions of P0 and L10 are responsible for binding of the cognate stalk dimers and ribosomal specificity for translation factors and suggest that the extended region participates in accessibility only for eukaryotic factors.