| Literature DB >> 6427753 |
G Giannini, R Rappuoli, G Ratti.
Abstract
The amino-acid sequences of two diphtheria toxin-related, non-toxic proteins, CRM45 and CRM197 , were deduced from the complete sequence of their genes: tox 45 and tox 197. CRM45 lacks the last 149 C-terminal amino-acid residues, but is otherwise identical to diphtheria toxin: a single C----T transition introduces an "ochre" (TAA) termination signal in tox 45, after the codon for threonine-386. A single G----A transition was also found in tox 197, leading to the substitution of glycine-52, present in the wild-type toxin, with glutamic acid in CRM197 . This aminoacid change is responsible for the loss of the NAD:EF2 ADP-ribosyltransferase activity in CRM197 , due most probably to an alteration of the NAD+ binding site.Entities:
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Year: 1984 PMID： 6427753 PMCID： PMC318816 DOI： 10.1093/nar/12.10.4063
Source DB: PubMed Journal: Nucleic Acids Res ISSN： 0305-1048 Impact factor: 16.971