NusA Is Required for Ribosomal Antitermination and for Modulation of the Transcription Elongation Rate of both Antiterminated RNA and mRNA*
NusA Is Required for Ribosomal Antitermination and for Modulation of the Transcription Elongation Rate of both Antiterminated RNA and mRNA*
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DOI：
10.1074/jbc.272.19.12265
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发表时间：
1997-05
期刊：
影响因子：
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通讯作者：
U. Vogel;K. Jensen
中科院分区：
文献类型：
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作者：
U. Vogel;K. Jensen
由于核糖体RNA(RRNA)转录本的5‘端存在抗终止序列，rRNA在体内的伸长速度是mRNA的两倍。许多NUS因子与RNA聚合酶的反终止位点结合，有助于抵抗依赖Rho的转录终止。本文研究了nusAcs10等位基因对核糖核酸和抗终止核糖核酸伸长率的影响。结果表明，NusA是实现携带核糖体抗终止盒的RNA链高伸长率所必需的，当转录伸长率被nusAcs10等位基因降低时，抗终止性是有缺陷的。此外，nusAcs10等位基因在稳态生长过程中对正常的allacZ基因的伸长率没有显著影响，但它取消了鸟苷3‘，5’-二(二磷酸)(PpGpp)对LacZ基因的伸长的抑制作用。这些结果表明，NusA是ppGpp抑制mRNA延伸所需的转录延伸复合体的组成部分。
Ribosomal RNA (rRNA) is elongated twice as fast as mRNA in vivo due to the presence of antitermination sequences in the 5′ part of the rRNA transcripts. A number of Nus factors bind to RNA polymerase at the antitermination sites and help confer resistance to Rho-dependent termination of transcription. In this paper, the effects of the nusAcs10allele on the elongation rate of both mRNA and antiterminated RNA were investigated. The results indicate that NusA is required to achieve a high elongation rate of RNA chains carrying the ribosomal antitermination boxA and that antitermination is defective when the rate of transcription elongation is decreased by thenusAcs10 allele. Furthermore, the nusAcs10allele had no significant effects on the elongation rate of normallacZ mRNA during steady state growth, but it abolished the inhibition of lacZ mRNA elongation by guanosine 3′,5′-bis(diphosphate) (ppGpp). These results suggest that NusA is the component of the transcription elongation complex required for inhibition of mRNA elongation by ppGpp.