Background

In last year's Nickel Hunter 2.0, we found that the nikABCDE system present in other strains of E. coli belongs to the ATP-binding cassette (ABC) protein family, and contains five proteins that can transport the hydrolyzed ATP to the transmembrane transport of nickel ions. NikB and NikC are two transmembrane proteins that form the transmembrane core of the transport system. NikA is a periplasmic binding protein (PBP) that transmits captured nickel ions to the NikBC core. NikD and NikE act as two cytoplasmic proteins. The signal-to-noise ratio of the system is increased by the nickel ion channel protein, and the detection accuracy is improved.

Inspiration

His-tag histidine tags can interact with various metal ions, including Ca²⁺, Mg²⁺, Ni²⁺+, Co²⁺, etc. Among them, nickel ions are most widely used. It fuses multiple histidine strands (commonly 6 histidine) at the end of the recombinant protein. By using this histidine peptide segment to chelate with divalent metal ions (nickel, zinc, etc.), nickel ions can be adsorbed.

Methods

In order to improve the adsorption efficiency of nickel ions this year, we added His-tag sequences on both 3’ and 5’ ends of nikABCDE, which is like adding a pair of hands to last year's nikABCDE proteins to optimize it.

Results

Two kinds of engineered bacteria were cultured in 30 mg/L nickel ion solution. Within 30 minutes, the original bacteria (nikABCDE) reduced the concentration of nickel ions from 30 mg/L to 15 mg/mL, but the improved engineered bacteria.

(His-Tag-nikABCDE-His-Tag) reduced the concentration of nickel ions from 30 mg/L to 10 mg/mL. It can be seen from the figure that the improved engineered bacteria has a stronger nickel adsorption ability than the original bacteria.