Structure and dynamics of the quaternary hunchback mRNA translation repression complex

Nucleic Acids Res. 2021 Sep 7;49(15):8866-8885. doi: 10.1093/nar/gkab635.

Abstract

A key regulatory process during Drosophila development is the localized suppression of the hunchback mRNA translation at the posterior, which gives rise to a hunchback gradient governing the formation of the anterior-posterior body axis. This suppression is achieved by a concerted action of Brain Tumour (Brat), Pumilio (Pum) and Nanos. Each protein is necessary for proper Drosophila development. The RNA contacts have been elucidated for the proteins individually in several atomic-resolution structures. However, the interplay of all three proteins during RNA suppression remains a long-standing open question. Here, we characterize the quaternary complex of the RNA-binding domains of Brat, Pum and Nanos with hunchback mRNA by combining NMR spectroscopy, SANS/SAXS, XL/MS with MD simulations and ITC assays. The quaternary hunchback mRNA suppression complex comprising the RNA binding domains is flexible with unoccupied nucleotides functioning as a flexible linker between the Brat and Pum-Nanos moieties of the complex. Moreover, the presence of the Pum-HD/Nanos-ZnF complex has no effect on the equilibrium RNA binding affinity of the Brat RNA binding domain. This is in accordance with previous studies, which showed that Brat can suppress mRNA independently and is distributed uniformly throughout the embryo.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Body Patterning / genetics
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / ultrastructure
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / ultrastructure
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / growth & development
  • Embryonic Development / genetics*
  • Gene Expression Regulation, Developmental
  • Multiprotein Complexes / genetics
  • Multiprotein Complexes / ultrastructure
  • Nuclear Magnetic Resonance, Biomolecular
  • Protein Structure, Quaternary
  • RNA Recognition Motif Proteins / genetics
  • RNA Recognition Motif Proteins / ultrastructure
  • RNA-Binding Proteins / genetics*
  • RNA-Binding Proteins / ultrastructure
  • Scattering, Small Angle
  • Transcription Factors / genetics*
  • Transcription Factors / ultrastructure
  • X-Ray Diffraction

Substances

  • DNA-Binding Proteins
  • Drosophila Proteins
  • Multiprotein Complexes
  • RNA Recognition Motif Proteins
  • RNA-Binding Proteins
  • Transcription Factors
  • brat protein, Drosophila
  • hb protein, Drosophila
  • pum protein, Drosophila
  • nos protein, Drosophila