Molecular basis of mRNA delivery to the bacterial ribosome

Science. 2024 Nov 29;386(6725):eado8476. doi: 10.1126/science.ado8476. Epub 2024 Nov 29.

Abstract

Protein synthesis begins with the formation of a ribosome-messenger RNA (mRNA) complex. In bacteria, the small ribosomal subunit (30S) is recruited to many mRNAs through base pairing with the Shine-Dalgarno (SD) sequence and RNA binding by ribosomal protein bS1. Translation can initiate on nascent mRNAs, and RNA polymerase (RNAP) can promote the recruitment of the pioneering 30S. Here, we examined 30S recruitment to nascent mRNAs using cryo-electron microscopy, single-molecule fluorescence colocalization, and in-cell cross-linking mass spectrometry. We show that bS1 delivers the mRNA to the ribosome for SD duplex formation and 30S activation. Additionally, bS1 and RNAP stimulate translation initiation. Our work provides a mechanistic framework for how the SD duplex, ribosomal proteins, and RNAP cooperate in 30S recruitment to mRNAs and establish transcription-translation coupling.

MeSH terms

  • Cryoelectron Microscopy*
  • DNA-Directed RNA Polymerases* / chemistry
  • DNA-Directed RNA Polymerases* / metabolism
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / genetics
  • Escherichia coli Proteins / metabolism
  • Peptide Chain Initiation, Translational
  • Protein Biosynthesis
  • RNA, Bacterial / chemistry
  • RNA, Bacterial / metabolism
  • RNA, Messenger* / chemistry
  • RNA, Messenger* / genetics
  • RNA, Messenger* / metabolism
  • Ribosomal Proteins* / chemistry
  • Ribosomal Proteins* / metabolism
  • Ribosome Subunits, Small, Bacterial / chemistry
  • Ribosome Subunits, Small, Bacterial / metabolism
  • Ribosomes / metabolism
  • Single Molecule Imaging
  • Transcription, Genetic

Substances

  • RNA, Messenger
  • Ribosomal Proteins
  • DNA-Directed RNA Polymerases
  • RNA, Bacterial
  • Escherichia coli Proteins