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Bacteriophage T7 mRNA is polyadenylated
Author(s) -
Johnson M. D.,
Popowski J.,
Cao G.J.,
Shen P.,
Sarkar N.
Publication year - 1998
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1998.00649.x
Subject(s) - polyadenylation , biology , bacteriophage , microbiology and biotechnology , rna , messenger rna , complementary dna , rnase p , coding region , cdna library , population , gene , genetics , escherichia coli , demography , sociology
To determine whether the RNA of bacterial viruses is polyadenylated like bacterial mRNAs, pulse‐labelled as well as the steady‐state population of bacteriophage T7‐specific transcripts were examined for the presence of poly(A) tracts by binding to oligo(dT) cellulose followed by hybridization with specific gene probes. Representatives of all classes of bacteriophage‐specific mRNA — early, middle and late — were found to be polyadenylated. This conclusion was confirmed by screening the products of oligo(dT)‐dependent cDNA synthesis. A cDNA library was prepared from RNA synthesized after bacteriophage T7 infection and the sequence of bacteriophage‐specific clones was determined to define the sites of polyadenylation. About half of the clones were polyadenylated near the end of a protein‐coding region, one of them at the site of post‐transcriptional processing by RNase III. Other clones were polyadenylated within protein‐coding regions. These observations suggest that polyadenylation occurs after the nucleolytic processing of primary transcripts and in some cases also after mRNA degradation has already begun.