ADP-Ribosylation of Cerebrocortical Synaptosomal Proteins by Cholera, Pertussisand Botulinum Toxins

摘要

Certain microbial toxins ADP-ribosylate G proteins that may be related to thosepostulated to participate in secretion, whilst botulinum neurotoxins, produced by Clostridium botulinum, block Ca2+ dependent neurotransmitter release. Thus, botulinum, pertussis and cholera toxins were examined for ADP-ribosyl transferase activity using isolated nerve terminals. Although type D botulinum, cholera, and pertussis toxins exhibited such enzymic activity, this was not detectable with types A or B botulinum, type D and pertussis toxins, or ADP-ribosylated proteins with mol. wt 24,000 and 42,000 respectively; whereas cholera toxin modified several proteins, including a 51,000/47,000 mol. wt doublet. Pre-incubation of synaptosomes with type A, B, or D toxins did not inhibit type D-induced labelling in the corresponding lysate. Similar pre-incubations with cholera or pertussis toxins reduced ADP-ribosylation of their substrates.