title: Nucleotide binding by a 24-residue peptide from the RecA protein of Escherichia coli.
abstract: We have recently demonstrated that two ATP analog affinity labels, 8-azidoadenosine 5'-triphosphate (N3ATP) and 5'-p-fluorosulfonylbenzoyladenosine (5'FSBA), covalently modify RecA protein of Escherichia coli at a specific tyrosine residue (Tyr-264) located within a 24-residue tryptic peptide (T-31) spanning residues 257-280. Here we show that N3ATP efficiently modifies purified peptide T-31 and show that the interaction is specific by the following criteria: photolabeling of peptide T-31 is saturable with respect to the N3ATP concentration; photolabeling is competitive with ATP and adenosine but not with adenine, UTP, or TTP; and other peptides derived from RecA protein were poor substrates for photolabeling except for one fragment that showed a nonspecific interaction with the photoaffinity analog. Analysis of N3ATP-modified T-31 shows that the photolabel attaches to more than one site within the peptide. These data argue that peptide T-31 contains some sites of contact for adenine and ribose moieties of ATP when it is bound to RecA protein.
mesh_terms: D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism*; D000345:Affinity Labels; D000595:Amino Acid Sequence; D001665:Binding Sites; D004926:Escherichia coli; D010446:Peptide Fragments / Q000378:metabolism; D010777:Photochemistry; D011485:Protein Binding; D011938:Rec A Recombinases / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D000345:Affinity Labels; D010446:Peptide Fragments; D000255:Adenosine Triphosphate; D011938:Rec A Recombinases