Ribosomal protein S4 acts in trans as a translational repressor to regulate expression of the alpha operon in Escherichia coli.

Journal Article (Journal Article)

Ribosomal protein (r-protein) S4 is the translational repressor which regulates the synthesis rates of r-proteins whose genes are in the alpha operon: r-proteins S13, S11, S4, and L17. In a strain having a mutation in the gene for r-protein S4 (rpsD), the mutant S4 fails to regulate expression of the alpha operon, resulting in specific and significant overproduction of r-proteins S13, S11, and S4. This confirms and extends similar observations made with rpsD mutants (M. O. Olsson and L. A. Isaksson, Mol. Gen. Genet. 169:271-278, 1979) before post-transcriptional regulation of r-protein synthesis was proposed and is consistent with the established regulatory role of r-protein S4. The rpsD mutant has been used to study the question of whether regulatory r-proteins function in trans or strictly in cis as translational repressors. The mutant strain was lysogenized with one or two specialized transducing phages carrying a wild-type S4 gene to obtain strains which were diploid or triploid with respect to the alpha operon. The wild-type and mutant forms of S4 were separated by two-dimensional polyacrylamide gel electrophoresis, which allowed accurate measurement of the relative contributions of r-proteins from different alpha operons within a single cell. We found that expression of r-proteins from the chromosomal alpha operon containing the rpsD allele was reduced when the wild-type S4 was present, with the effect being greater in the triploid strain than in the diploid strain. We conclude that the wild-type S4 acts in trans as a translational repressor to regulate expression from the chromosomal alpha operon.

Full Text

Duke Authors

Cited Authors

  • Jinks-Robertson, S; Nomura, M

Published Date

  • July 1982

Published In

Volume / Issue

  • 151 / 1

Start / End Page

  • 193 - 202

PubMed ID

  • 6211432

Pubmed Central ID

  • PMC220226

International Standard Serial Number (ISSN)

  • 0021-9193

Digital Object Identifier (DOI)

  • 10.1128/jb.151.1.193-202.1982


  • eng

Conference Location

  • United States