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Three conserved consensus sequences identify the NAD‐binding site of ADP‐ribosylating enzymes, expressed by eukaryotes, bacteria and T‐even bacteriophages
Author(s) -
Domenighini Mario,
Rappuoli Rino
Publication year - 1996
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1996.321396.x
Subject(s) - nad+ kinase , enzyme , biochemistry , biology , residue (chemistry) , conserved sequence , amino acid , binding site , bacteria , stereochemistry , peptide sequence , chemistry , genetics , gene
It has been previously reported that the three‐dimensional structures of the NAD‐binding and catalytic site of bacterial toxins with ADP‐ribosylating activity are superimposable, and that the key amino acids for the enzymatic activity are conserved. The model includes an NAD‐binding and catalytic site formed by an α‐helix bent over a β‐strand, surrounded by two β‐strands bearing a Glu and a His, or Arg, that are required for catalysis. We show here that the model can be extended to comprise all proteins with ADP‐ribosylating activity known to date, including all eukaryotic mono‐ and poly‐ADP‐ribosyltransferases, the bacterial ADP‐ribosylating enzymes which do not have toxic activity, and the analogous enzymes encoded by T‐even bacteriophages. We show that, in addition to the common Glu and Arg/His amino acids previously identified, the conserved motifs can be extended as follows: (i) the Arg/His motif is usually arom‐His/Arg (where ‘arom’ is an aromatic residue); (ii) in the sequences of the CT group the β‐strand forming part of the ‘scaffold’ of the catalytic cavity has an arom‐ph‐Ser‐Thr‐Ser‐ph consensus (where ‘ph’ represents a hydrophobic residue); and (iii) the motif centred in the key glutamic residue is Glu/Gln‐X‐Glu; while (iv) in the sequences of the DT group the NAD‐binding motif is Tyr‐X 10 ‐Tyr. We believe that the model proposed not only accounts for all ADP‐ribosylating proteins known to date, but it is likely to fit other enzymes (currently being analysed) which possess such an activity.