Structural rearrangement in an RsmA/CsrA ortholog of Pseudomonas aeruginosa creates a dimeric RNA-binding protein, RsmN

Structure. 2013 Sep 3;21(9):1659-71. doi: 10.1016/j.str.2013.07.007. Epub 2013 Aug 15.

Abstract

In bacteria, the highly conserved RsmA/CsrA family of RNA-binding proteins functions as global posttranscriptional regulators acting on mRNA translation and stability. Through phenotypic complementation of an rsmA mutant in Pseudomonas aeruginosa, we discovered a family member, termed RsmN. Elucidation of the RsmN crystal structure and that of the complex with a hairpin from the sRNA, RsmZ, reveals a uniquely inserted α helix, which redirects the polypeptide chain to form a distinctly different protein fold to the domain-swapped dimeric structure of RsmA homologs. The overall β sheet structure required for RNA recognition is, however, preserved with compensatory sequence and structure differences, allowing the RsmN dimer to target binding motifs in both structured hairpin loops and flexible disordered RNAs. Phylogenetic analysis indicates that, although RsmN appears unique to P. aeruginosa, homologous proteins with the inserted α helix are more widespread and arose as a consequence of a gene duplication event.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / chemistry*
  • Base Sequence
  • Binding Sites
  • Crystallography, X-Ray
  • Hydrogen Bonding
  • Hydrophobic and Hydrophilic Interactions
  • Inverted Repeat Sequences
  • Models, Molecular
  • Molecular Sequence Data
  • Protein Binding
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Pseudomonas aeruginosa*
  • RNA, Bacterial / chemistry
  • RNA-Binding Proteins / chemistry*

Substances

  • Bacterial Proteins
  • RNA, Bacterial
  • RNA-Binding Proteins

Associated data

  • PDB/4KJI
  • PDB/4KRW