Lundberg U, Altman S
Department of Biology, Yale University, New Haven, Connecticut 06520, USA.
RNA. 1995 May;1(3):327-34.
M1 RNA, the catalytic subunit of RNase P from Escherichia coli, is transcribed in vivo as a precursor with extra nucleotides at the 3' end. Although it was suggested previously that RNase E is not responsible for the 3' processing of M1 RNA, we show that RNase E is the enzyme responsible for this reaction. At nonpermissive temperatures, the 3' processing of M1 RNA is abolished in a temperature-sensitive strain of E. coli that harbors a mutation in the gene for RNase E. Enhanced processing of M1 RNA is correlated with the overproduction of RNase E in vivo and processing is also correlated with the activity of this enzyme during the course of its purification. The biosynthesis of mature M1 RNA can proceed from transcripts that are produced under the control of a proximal promoter, as well as from a distal, upstream promoter. Transcription from the distal promoter results in a polycistronic transcript that includes four open reading frames and the transcript of rnpB, the gene coding for M1 RNA. The enzymatic activity that removes the 5' nucleotides from the precursor to M1 RNA is not due to RNase E, RNase P, or RNase III alone.
M1 RNA是来自大肠杆菌的核糖核酸酶P的催化亚基，在体内转录时是一种3'端带有额外核苷酸的前体。尽管之前有人认为核糖核酸酶E不负责M1 RNA的3'端加工，但我们发现核糖核酸酶E是负责此反应的酶。在非允许温度下，M1 RNA的3'端加工在一株对温度敏感的大肠杆菌中被消除，该菌株的核糖核酸酶E基因发生了突变。M1 RNA加工的增强与核糖核酸酶E在体内的过量表达相关，并且加工也与该酶在纯化过程中的活性相关。成熟M1 RNA的生物合成可以从近端启动子控制下产生的转录本进行，也可以从远端上游启动子进行。从远端启动子转录产生一个多顺反子转录本，其中包括四个开放阅读框和rnpB（编码M1 RNA的基因）的转录本。从前体M1 RNA去除5'核苷酸的酶活性并非单独由核糖核酸酶E、核糖核酸酶P或核糖核酸酶III所致。
