A TEMPERATURE-DEPENDENT CONFORMATIONAL REARRANGEMENT IN THE RIBOSOMAL-PROTEIN S4-CENTER-DOT-16-S RIBOSOMAL-RNA COMPLEX
A TEMPERATURE-DEPENDENT CONFORMATIONAL REARRANGEMENT IN THE RIBOSOMAL-PROTEIN S4-CENTER-DOT-16-S RIBOSOMAL-RNA COMPLEX
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DOI：
10.1074/jbc.270.3.1238
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发表时间：
1995-01-20
影响因子：
4.8
通讯作者：
NOLLER, HF
中科院分区：
文献类型：
--
作者：
POWERS, T;NOLLER, HF
核糖体蛋白S4保护16s rRNA中的一组特征碱基免受化学探针的攻击。利用羟基自由基作为RNA主链的探针表明，这些相同区域的核糖残基也受到S4的保护，证实了其与16s rRNA的相互作用定位于5'结构域近端区域的五个螺旋元件的连接处。在0℃时，受S4保护的核苷酸几乎完全局限于由残基404-499形成的两个复合螺旋。随后在30或42℃下短暂加热复合物后，三个相邻螺旋中的核苷酸被额外保护，从而产生与在体外重构条件下54与16s rRNA孵育时观察到的保护模式相同。蛋白质或RNA（或两者）分别在高温下预孵育不能代替加热S4。RNA复杂。RNA中受热步骤影响的区域已知与蛋白质S12和S16相互作用，两者都依赖于54与RNA的结合。因此，54在RNA初始结合后募集了额外的相互作用位点，这一发现提示了一种可能的机制，以确保在核糖体组装过程中蛋白质的顺序添加。
Ribosomal protein S4 protects a characteristic set of bases in 16 S rRNA from attack by chemical probes. Use of hydroxyl radical as a probe of the RNA backbone shows that ribose residues in these same regions are also protected by S4, confirming the localization of its interactions with 16 S rRNA to the junction of five helical elements in the proximal region of the 5' domain. At 0 degrees C, the nucleotides protected by S4 from base-specific probes are confined almost exclusively to the two compound helices formed by residues 404-499. After subsequent heating of the complex briefly at 30 or 42 degrees C, nucleotides in the three adjacent helices are additionally protected, resulting in a pattern of protection that is identical to that which is observed when 54 is incubated with 16 S rRNA under in vitro reconstitution conditions. Preincubation of the protein or the RNA (or both) separately at elevated temperature does not substitute for heating the S4.RNA complex. The regions in the RNA affected by the heat step are known to interact with proteins S12 and S16, both of which depend upon 54 for their binding to the RNA. Thus, the finding that 54 recruits additional sites of interaction in the RNA following its initial binding suggests a possible mechanism to insure the sequential addition of proteins during ribosomal assembly.