Genetic modifications of metallothionein enhance the tolerance and bioaccumulation of heavy metals in Escherichia coli

Metallothioneins (MTs) are low molecular weight cysteine-rich proteins that bind to metals. Owing their high cysteine (Cys) content, MTs effective mediators of heavy metal detoxification. To enhance the binding ability MT from freshwater crab Sinopotamon henanense (ShMT), sequence-based multiple sequence alignment (MSA) and structure-based docking simulation (MDS) were conducted in order identify amino acid residues could be mutated bolster such metal-binding activity. Site-directed mutagenesis was then used modify primary structure ShMT, recombinant further enhanced using SUMO fusion expression system yield SUMO-ShMT1, SUMO-ShMT2, SUMO-ShMT3 harboring one-, two-, three- point mutations, respectively. The resultant modified primarily expressed a soluble form exhibited readily Importantly, these significantly capacities, they improved Cd2+, Cu2+ Zn2+ tolerance bioaccumulation Escherichia coli (E. coli) manner dependent upon number introduced mutations (SUMO-ShMT3 > SUMO-ShMT2 SUMO-ShMT1 SUMO-ShMT control). Indeed, E. cells pET28a-SUMO-ShMT3 vector maximal Cu2+, increased by 1.86 ± 0.02-, 1.71 0.03-, 2.13 0.02-fold relative pET28a-SUMO-ShMT vector. present study offers basis for preparation genetically engineered bacteria better able bioaccumulate tolerate metals, thus providing foundation biological water pollution treatment.