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Identification of Glu 173 as the critical amino acid residue for the ADP‐ribosyltransferase activity of Clostridium botulinum C3 exoenzyme
Author(s) -
Saito Yuji,
Nemoto Yasuo,
Ishizaki Toshimasa,
Watanabe Naoki,
Morii Narito,
Narumiya Shuh
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00851-y
Subject(s) - exoenzyme , clostridium botulinum , enzyme , nad+ kinase , biochemistry , adp ribosylation , mutagenesis , amino acid , chemistry , biology , mutant , toxin , gene
Clostridium botulinum C3 exoenzyme specifically ADP‐ribosylates rho‐p21 in eukaryotic cells. Trp 18 and Glu 173 of this enzyme were substituted with other amino acids via site‐directed mutagenesis. All substitutions at Glu 173 caused a significant reduction in affinity for NAD and diminished ADP‐ribosyltransferase activity. On the other hand, the activity of enzymes with the substitution at Trp 18 remained intact. Swiss 3T3 cells treated with the enzyme with the Trp 18 substitution showed the typical morphologic changes of the C3 exoenzyme phenotype. In contrast, no changes were found in cells incubated with the Glu 173 ‐substituted enzyme. These results indicate that the Glu 173 residue of the C3 exoenzyme plays a key role in interacting with NAD and in expression of ADP‐ribosyltransferase activity, which is essential for the phenotypic change by C3 exoenzyme treatment.