Evidence for the importance of electrostatics in the function of two distinct families of ribosome inactivating toxins.
RNA
; 13(9): 1391-6, 2007 Sep.
Article
en En
| MEDLINE
| ID: mdl-17626843
Alpha-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. alpha-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 approximately 10(9)-10(10) M(-1) s(-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.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas de Plantas
/
Ribosomas
/
Ricina
/
Ésteres del Ácido Sulfúrico
/
Triterpenos
/
Proteínas Fúngicas
/
Inhibidores de la Síntesis de la Proteína
/
Familia de Multigenes
/
Endorribonucleasas
/
N-Glicosil Hidrolasas
Idioma:
En
Revista:
RNA
Asunto de la revista:
BIOLOGIA MOLECULAR
Año:
2007
Tipo del documento:
Article
Pais de publicación:
Estados Unidos