Ml4 protein from Mesorhizobium loti has a 58% sequence identity with the Ros protein from Agrobacterium tumefaciens that contains a prokaryotic Cys(2)His(2) zinc finger domain. Interestingly, Ml4 is a zinc-lacking protein that does not contain the Cys(2)His(2) motif and is able to bind the Ros DNA target sequence with high affinity. Here we report the (1)H, (15)N and (13)C NMR assignments of the Ml4 protein DNA binding domain (residue 52-151), as an important step toward elucidating at a molecular level how this prokaryotic domain can overcome the metal requirement for proper folding and DNA-binding activity.