title: Comparative study on Ni(2+)-affinity transport of nickel/cobalt permeases (NiCoTs) and the potential of recombinant Escherichia coli for Ni(2+) bioaccumulation.
abstract: Comparative evaluation on Ni(2+)-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 Ni(2+) uptake of the recombinant strains and made the growth susceptible to Ni(2+). However, recombinant strains expressing both NiCoTs and Metallothionein (MT) showed enhanced tolerance to Ni(2+) and Ni(2+) uptake. The maximum Ni(2+)-uptake capacity of recombinant strain N1c expressing NixA+MT reached 83.33mgg(-1), higher than 45.45mgg(-1) of recombinant strain N1d expressing NisA+MT. N1c exhibited more effective Ni(2+) accumulation than N1d in the presence of Na(+), Co(2+) and Cd(2+). NiCoTs promoted intracellular Ni(2+) uptake of the recombinant strains. Phosphate groups dominated Ni(2+) binding of wild type Escherichia coli, but carboxyl groups contributed more for N1c and N1d. The result suggested that NixA has a higher specificity in Ni(2+) binding than NisA, and both NiCoTs and MT are important for Ni(2+) bioaccumulation.
authors.affiliation: College of Life Science, Shenzhen Key Laboratory of Microbial Genetic Engineering, Shenzhen University, Shenzhen 518060, PR China. dengxu@szu.edu.cn
authors.forename: Xu
authors.initials: X
authors.lastname: Deng
authors.forename: Jinmei
authors.initials: J
authors.lastname: He
authors.forename: Ning
authors.initials: N
authors.lastname: He
mesh_terms: D002104:Cadmium / Q000378:metabolism; D003035:Cobalt / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D016480:Helicobacter pylori / Q000235:genetics; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D009532:Nickel / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D013211:Staphylococcus aureus / Q000235:genetics
chemical_list: D026901:Membrane Transport Proteins; D011994:Recombinant Proteins; D002104:Cadmium; D003035:Cobalt; D009532:Nickel; D012964:Sodium