The low-affinity ATP binding site of the Escherichia coli secA dimer is localized at the subunit interface

Bifunctional photoactivatable nucleotide analogue 3'-arylazido-8-azidoadenosine 5'-triphosphate (diN3ATP) was utilized to probe the spatial arrangement of the nucleotide binding sites of the SecA dimer in Escherichia coli. Results have shown that crosslinking of the protein occurred at NBS2 located at the domain of SecA. UV irradiation resulted in the formation of crosslinked SecA dimers.