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Comparative evaluation on Ni2+-uptake of two nickel-affinity transmembrane proteins (NiCoTs) respectively from Helocobacter pylori (NixA) and Staphylococcus aureus (NisA) was performed.Expression of NiCoTs alone did not promote Ni2+ uptake of the recombinant strains and made the growth susceptible to Ni2+.However,recombinant strains expressing both NiCoTs and Metallothionein (MT) showed enhanced tolerance to Ni2+ and Ni2+-uptake.The maximum Ni2+-uptake capacity of recombinant strain N1c expression NixA+MT reached 83.33mg/g,higher than 45.45 mg/g of recombinant strain N1d expressing NisA+MT.N1e exhibited more effective Ni2+ accumulation than N1d in the presence of Na+,Co2+ and Cd2+.NiCoTs promoted intracellular Ni2+ uptake of the recombinant strains.Phosphate groups dominated Ni2+ binding of wild type E.coli,but carboxyl groups contributed more for N1c and N1d.The result suggested that NixA has a higher specificity in Ni2+ binding than NisA,and both NiCoTs and MT are important for Ni2+bioaccumulation.