Charge reversal of ammodytoxin A, a phospholipase A2-toxin, does not abolish its neurotoxicity.
The positive charge concentrated at the C-terminal region of ammodytoxin (Atx) A, which is involved in presynaptic toxicity, has been reversed. A six-site mutant of AtxA (K108N/K111N/K127T/K128E/E129T/K132E , where K108N=Lys(108)-->Asn etc. ) was prepared, in which five out of seven C-terminal basic amino acid residues were substituted with neutral or acidic ones. The mutant was approximately 30-fold less lethal, but still neurotoxic. Consistent with this, its binding affinity for the neuronal receptors decreased by only a factor of five. Additionally, a single-site mutant of AtxA was prepared, with substitution at only one position (K127T) out of six mutated in the six-site mutant. Its toxicity indicated that most, if not all, of the six mutated residues partially contribute to the decreased lethality of the multiple-site mutant.
Prijatelj
P
P
Faculty of Chemistry and Chemical Technology, University of Ljubljana, Askerceva 5, SI-1000 Ljubljana, Slovenia.
Copic
A
A
Krizaj
I
I
Gubensek
F
F
Pungercar
J
J
D000595:Amino Acid Sequence; D001483:Base Sequence; D017931:DNA Primers; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009420:Nervous System / Q000187:drug effects*; D010741:Phospholipases A / Q000737:chemistry / Q000235:genetics / Q000633:toxicity*; D054467:Phospholipases A2; D011487:Protein Conformation; D011869:Radioligand Assay; D017386:Sequence Homology, Amino Acid; D014757:Viper Venoms / Q000737:chemistry / Q000235:genetics / Q000633:toxicity*
D017931:DNA Primers; D014757:Viper Venoms; C068117:ammodytoxin A; D010741:Phospholipases A; D054467:Phospholipases A2