期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1992
卷号：89
期号：16
页码：7546-7550
DOI：10.1073/pnas.89.16.7546
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Although it has been known for some time that bacterial mRNA molecules carry polyadenylate moieties at their 3' ends, nothing is known about the molecular structure of bacterial poly(A) RNA. To define the polyadenylylation site of a specific bacterial mRNA, we took advantage of the presence of elevated levels of poly(A) RNA in cells of Escherichia coli deficient in exoribonucleases and synthesized DNA complementary to polyadenylylated lipoprotein mRNA, encoded by the lpp gene, by using avian myeloblastosis virus reverse transcriptase and an oligo(dT)-containing primer. The 5'-terminal portion of the cDNA was amplified by the polymerase chain reaction and appropriate oligonucleotide primers, and the amplified DNA was cloned in pUC18 and subjected to nucleotide sequence analysis. Four clones were found to contain the entire 3'-terminal coding region of lpp mRNA, with poly(A) attached to either of two sites in the downstream untranslated region of the transcript. In one type of clone, the polyadenylate moiety was attached at the putative transcription termination site of lpp mRNA, whereas other clones lacked the stem-loop structure of the rho-independent transcription terminator and the polyadenylate moiety was attached to the residue just preceding the terminal stem-loop of the primary transcript. A model for the polyadenylylation of bacterial mRNA is proposed in which poly(A) polymerase and exonucleases compete for the 3' ends of mRNA molecules.
