Metal Ion Sensor of Pore-Forming Toxin for Environmental Evaluation

Abstract

Today, one of the materials attracting attention in the nanotechnology field includes proteinaceous toxins (pore-forming toxins, PFTs) that form nanosize pores in cell membranes. They originally attracted attention as bacterial virulence factors, with which research has been conducted on their biological effects on human beings and animals. In the 1980s, it was found that PFTs, when coming into contact with membranes, were transformed from water-soluble proteins into membrane proteins, causing pores (ion channels) to form in the target membrane. They have been studied by protein chemists and X-ray crystallographers. In the twenty-first century, PFTs that have pores about the size of 2 nm could be made available in a large quantity through genetic recombination at any time. Interesting research on nanotechnology started after such availability was noted by nanotechnology researchers. This chapter is a review mainly based on the author’s research findings that the PFT becomes a new probe that works as a metal ion sensor.