RNase T affects Escherichia coli growth and recovery from metabolic stress

K. P. Padmanabha, M. P. Deutscher

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20 Scopus citations


To determine the essentiality and role of RNase T in RNA metabolism, we constructed an Escherichia coli chromosomal rnt::kan mutation by using gene replacement with a disrupted, plasmid-borne copy of the rnt gene. Cell extracts of a strain with mutations in RNases BN, D, II, and I and an interrupted rnt gene were devoid of RNase T activity, although they retained a low level (<10%) of exonucleolytic activity on tRNA-C-C[14C]A due to two other unidentified RNases. A mutant lacking tRNA nucleotidyltransferase in addition to the aforementioned RNAses accumulated only about 5% as much defective tRNA as did RNase T-positive cells, indicating that this RNase is responsible for essentially all tRNA end turnover in E. coli. tRNA from rnt::kan strains displayed a slightly reduced capacity to be aminoacylated, raising the possibility that RNase T may also participate in tRNA processing. Strains devoid of RNase T displayed slower growth rates than did the wild type, and this phenotype was accentuated by the absence of the other exoribonucleases. A strain lacking RNase T and other RNases displayed a normal response to UV irradiation and to the growth of bacteriophages but was severely affected in its ability to recover from a starvation regimen. The data demonstrate that the absence of RNase T affects the normal functioning of E. coli, but it can be compensated for to some degree by the presence of other RNases. Possible roles of RNase T in RNA metabolism are discussed.

Original languageEnglish (US)
Pages (from-to)1376-1381
Number of pages6
JournalJournal of bacteriology
Issue number4
StatePublished - 1991

ASJC Scopus subject areas

  • Microbiology
  • Molecular Biology


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