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Photoaffinity labeling experiments with diphtheria toxin fragment A have implicated glutamic acid 148 as a constituent of the NAD binding site. To evaluate the role of this residue in ADP-ribosylation of elongation factor 2, we replaced it with aspartic acid by in vitro mutagenesis of a toxin gene fragment cloned in Escherichia coli. Fragment A containing aspartic acid at position 148 had less than 0.6% the ADP-ribosylation activity of wild-type fragment A. The mutation produced no change in sensitivity of fragment A to trypsin and little, if any, reduction in affinity of fragment A for NAD. These results indicate that glutamic acid 148 is essential for the ADP-ribosylation of elongation factor 2 and are consistent with other data suggesting that this residue may be at or near the catalytic center of the toxin.
R K Tweten, and
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R J Collier
September 1990,
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R K Tweten, and
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April 1990,
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R K Tweten, and
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R K Tweten, and
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R K Tweten, and
J T Barbieri, and
R J Collier
January 1997,
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R K Tweten, and
J T Barbieri, and
R J Collier
June 1988,
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R K Tweten, and
J T Barbieri, and
R J Collier
June 1987,
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R K Tweten, and
J T Barbieri, and
R J Collier
April 1984,
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R K Tweten, and
J T Barbieri, and
R J Collier
April 2020,
ACS infectious diseases,
R K Tweten, and
J T Barbieri, and
R J Collier
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Journal of bacteriology,
