The structural features of an ancient ribonuclease from Salmo salar reveal an intriguing case of auto-inhibition

Int J Biol Macromol. 2021 Jul 1:182:659-668. doi: 10.1016/j.ijbiomac.2021.04.041. Epub 2021 Apr 16.

Abstract

The superfamily of vertebrate ribonucleases, a large group of evolutionarily related proteins, continues to provide interesting structural and functional information. In particular, the crystal structure of SS-RNase-2 from Salmo salar (SS2), here presented, has revealed a novel auto-inhibition mechanism that enriches the number of inhibition strategies observed in some members of the family. Within an essentially unmodified RNase folding, the SS2 active site cleft is in part obstructed by the collapse of an extra pentapeptide inserted in the C-terminal region. This unexpected intrusion alters the organization of the catalytic triad by pushing one catalytic histidine off the pocket. Possible mechanisms to remove the active site obstruction have also been studied through the production of two mutants that provide useful information on the functionality of this intriguing version of the ribonuclease superfamily.

Keywords: Auto-inhibition; Crystal structure; Evolution; Ribonucleases.

MeSH terms

  • Animals
  • Evolution, Molecular
  • Fish Proteins / chemistry*
  • Fish Proteins / genetics
  • Fish Proteins / metabolism
  • Protein Domains
  • Protein Folding
  • Ribonucleases / chemistry*
  • Ribonucleases / genetics
  • Ribonucleases / metabolism
  • Salmo salar / metabolism

Substances

  • Fish Proteins
  • Ribonucleases