Evidence for the importance of electrostatics in the function of two distinct families of ribosome inactivating toxins

Alexei V. Korennykh, Carl C. Correll, Joseph A. Piccirilli

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

α-Sarcin and ricin represent two structurally and mechanistically distinct families of site-specific enzymes that block translation by irreversibly modifying the sarcin/ricin loop (SRL) of 23S-28S rRNA. α-Sarcin family enzymes are designated as ribotoxins and act as endonucleases. Ricin family enzymes are designated as ribosome inactivating proteins (RIP) and act as N-glycosidases. Recently, we demonstrated that basic surface residues of the ribotoxin restrictocin promote rapid and specific ribosome targeting by this endonuclease. Here, we report that three RIP: ricin A, saporin, and gypsophilin depurinate the ribosome with strong salt sensitivity and achieve unusually fast kcat/Km ∼10 9-1010 M-1s-1, implying that RIP share with ribotoxins a common mechanism of electrostatically facilitated ribosome targeting. Bioinformatics analysis of RIP revealed that surface charge properties correlate with the presence of the transport chain in the RIP molecule, suggesting a second role for the surface charge in RIP transport. These findings put forward surface electrostatics as an important determinant of RIP activity. Published by Cold Spring Harbor Laboratory Press.

Original languageEnglish (US)
Pages (from-to)1391-1396
Number of pages6
JournalRNA
Volume13
Issue number9
DOIs
StatePublished - Sep 2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Molecular Biology

Keywords

  • Electrostatic
  • Kinetics
  • Mechanism
  • Ribosome
  • Ribotoxin
  • Smoluchowski

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