Relationship between protein synthesis and concentrations of charged and uncharged tRNATrp in Escherichia coli

Mumtaz V. Rojiani, Hleronim Jakubowski, Emanuel Goldman

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28 Scopus citations


We have continuously monitored Trp-tRNATrp concentrations in vivo and, in the same cultures, measured rates of protein synthesis in isogenic stringent and relaxed strains. We have also manipulated cellular charged and uncharged [tRNATrp] by two means: (i) the strain used contains a Trp-tRNA synthetase mutation that increases the Km for Trp; thus, varying exogenous Trp varies cellular Trp-tRNATrp; and (ii) we have introduced into the mutant strain a plasmid containing the tRNATrp gene behind an inducible promoter; thus, total [tRNATrp] also can be varied depending on length of induction. The use of these conditions, combined with a previously characterized assay system, has allowed us to demonstrate that (i) the rate of incorporation of Trp into protein is proportional to the fraction of tRNATrp that is charged; for any given total [tRNATrp], this rate is also proportional to the [Trp-tRNATrp]; (H) uncharged tRNATrp inhibits incorporation of Trp into protein; and (iii) rates of incorporation into protein of at least two other amino acids, Lys and Cys, are also sensitive to [Trp-tRNATrp] and are inhibited by uncharged tRNATrp. Our results are consistent with models of translational control that postulate modulating polypeptide chain elongation efficiency by varying concentrations of specific tRNAs.

Original languageEnglish (US)
Pages (from-to)1511-1515
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number4
StatePublished - 1990

All Science Journal Classification (ASJC) codes

  • General


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