TY - JOUR
T1 - Histidine-44 of the A subunit of Escherichia coli enterotoxin is involved in its enzymatic and biological activities
AU - Kato, Michio
AU - Imamura, Seiji
AU - Kawase, Hidetsugu
AU - Miyama, Akio
AU - Tsuji, Takao
N1 - Funding Information:
This work was supported by a grant-in-aid for scientific research from the Ministry of Education, Science and Culture of Japan.
PY - 1997/7/15
Y1 - 1997/7/15
N2 - We examined the role in toxicity of histidine-44 of the A subunit of Escherichia coli enterotoxin which is located in the active site cavity close to glutamic acid-112. Although amino acid substitution of histidine-44 usually renders a mutant toxin unstable to trypsin, one mutant, alanine-44 (His44Ala) was found to be stable. His44Ala did not show any agmatine:ADP- ribosyltransferase activity in the presence or absence of recombinant ADP- ribosylation factor. It showed no diarrheal or rabbit skin permeability activity and was a competitor in enterotoxin-ADP-ribosyltransferase assays containing recombinant ADP-ribosylation factor. These results suggest that like glutamic acid-112, histidine-44 plays an essential role in toxicity. A tentative model, which explains NAD+ catalysis and the transfer of the ADP- ribosyl moiety to a target amino acid, is proposed for histidine-44 and glutamic acid-112.
AB - We examined the role in toxicity of histidine-44 of the A subunit of Escherichia coli enterotoxin which is located in the active site cavity close to glutamic acid-112. Although amino acid substitution of histidine-44 usually renders a mutant toxin unstable to trypsin, one mutant, alanine-44 (His44Ala) was found to be stable. His44Ala did not show any agmatine:ADP- ribosyltransferase activity in the presence or absence of recombinant ADP- ribosylation factor. It showed no diarrheal or rabbit skin permeability activity and was a competitor in enterotoxin-ADP-ribosyltransferase assays containing recombinant ADP-ribosylation factor. These results suggest that like glutamic acid-112, histidine-44 plays an essential role in toxicity. A tentative model, which explains NAD+ catalysis and the transfer of the ADP- ribosyl moiety to a target amino acid, is proposed for histidine-44 and glutamic acid-112.
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U2 - 10.1016/S0378-1097(97)00200-0
DO - 10.1016/S0378-1097(97)00200-0
M3 - Article
C2 - 9231414
AN - SCOPUS:0030745476
SN - 0378-1097
VL - 152
SP - 219
EP - 225
JO - FEMS Microbiology Letters
JF - FEMS Microbiology Letters
IS - 2
ER -