Translation initiation in bacterial polysomes through ribosome loading on a standby site on a highly translated mRNA

Proc Natl Acad Sci U S A. 2018 Apr 24;115(17):4411-4416. doi: 10.1073/pnas.1718029115. Epub 2018 Apr 9.

Abstract

During translation, consecutive ribosomes load on an mRNA and form a polysome. The first ribosome binds to a single-stranded mRNA region and moves toward the start codon, unwinding potential mRNA structures on the way. In contrast, the following ribosomes can dock at the start codon only when the first ribosome has vacated the initiation site. Here we show that loading of the second ribosome on a natural 38-nt-long 5' untranslated region of lpp mRNA, which codes for the outer membrane lipoprotein from Escherichia coli, takes place before the leading ribosome has moved away from the start codon. The rapid formation of this standby complex depends on the presence of ribosomal proteins S1/S2 in the leading ribosome. The early recruitment of the second ribosome to the standby site before translation by the leading ribosome and the tight coupling between translation elongation by the first ribosome and the accommodation of the second ribosome can contribute to high translational efficiency of the lpp mRNA.

Keywords: global fitting; polysome formation; ribosome; translation initiation; translational efficiency.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Outer Membrane Proteins / biosynthesis*
  • Bacterial Outer Membrane Proteins / genetics
  • Escherichia coli / genetics
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins / biosynthesis*
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Lipoproteins / biosynthesis*
  • Lipoproteins / genetics
  • Peptide Chain Initiation, Translational / physiology*
  • Polyribosomes / genetics
  • Polyribosomes / metabolism*
  • RNA, Bacterial / genetics
  • RNA, Bacterial / metabolism*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism*
  • Ribosomal Proteins / genetics
  • Ribosomal Proteins / metabolism

Substances

  • Bacterial Outer Membrane Proteins
  • Escherichia coli Proteins
  • Lipoproteins
  • Lpp protein, E coli
  • RNA, Bacterial
  • RNA, Messenger
  • Ribosomal Proteins
  • ribosomal protein S1, E coli
  • ribosomal protein S2