Insertional mutagenesis of ricin A chain: a novel route to an anti-ricin vaccine.
The insertion of a specific 25-residue internal peptide into ricin toxin A chain (RTA) reduced the catalytic activity of this protein approximately 300-fold. Directed proteolytic cleavage of the peptide insert essentially restored catalytic activity of the resulting two peptide A chain to normal levels. Ricin holotoxin containing unprocessed mutant A chain was not toxic to cultured mammalian cells, due to enhanced proteasomal degradation, nor was it toxic when injected into rats at a concentration that is lethal in the case of native ricin. Rats treated in this way were completely resistant to native ricin when subsequently challenged with a potentially lethal dose of the toxin. These ricin-resistant animals had a significant anti-ricin antibody titer, indicating that this approach has potential for developing an effective vaccine against this toxin.
Marsden
Catherine J
CJ
Department of Biological Sciences, University of Warwick, Coventry, CV4 7AL, UK. cmarsden@bio.warwick.ac.uk
Knight
Simon
S
Smith
Daniel C
DC
Day
Philip J
PJ
Roberts
Lynne M
LM
Phillips
Gary J
GJ
Lord
J Michael
JM
D000595:Amino Acid Sequence; D000818:Animals; D002384:Catalysis; D002470:Cell Survival / Q000187:drug effects; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000378:metabolism; D006868:Hydrolysis; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D012335:RNA, Ribosomal / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D012270:Ribosomes / Q000276:immunology; D012276:Ricin / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D012278:Ricinus / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000648:ultrastructure; D012697:Serine Endopeptidases / Q000737:chemistry; D003313:Zea mays / Q000276:immunology
D012335:RNA, Ribosomal; D012276:Ricin; D006026:Glycoside Hydrolases; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase