Enterotoxin C2 superantigen mutant proteins, and coding gene and preparation and application thereof

Abstract

The invention relates to enterotoxin C2 superantigen mutant proteins, and a coding gene and preparation and application thereof. The enterotoxin C2 superantigen mutant proteins SAM-1, SAM-2 and SAM-3 respectively have amino acid sequences of SEQID NO:2, SEQID NO:4 and SEQID NO:6 shown in a sequence table; the preparation process comprises the following steps of: performing overlap PCR amplification by taking a DNA segment having a base sequence of SEQID NO:7 in the sequence table as a template; performing PCR amplification by taking sec2-F and sec2-R as primers and an overlap PCR product as a template to obtain a mutant gene; cloning the mutant gene in an expression vector pET-28a, and constructing into a gene engineering bacterium for heterologously expressing each enterotoxin C2 superantigen mutant protein by taking escherichia coli BL21(DE3) as a host bacterium; and inducing and heterologously expressing to obtain each enterotoxin C2 superantigen mutant protein. The mutant proteins keep higher super-antigen activity and tumor suppressing activity, have obviously reduced emetic activity and febrifacient activity compared with the wild enterotoxin C2 protein, and have better clinical medication prospect.

Description

technical field [0001] The invention relates to an enterotoxin C2 superantigen mutant protein, specifically an enterotoxin C2 superantigen mutant protein with medicinal prospects, a coding gene and its preparation and application. Background technique [0002] Superantigen (SAg) is a group of protein molecules encoded by bacteria or viruses, which have strong immunostimulatory activity on human or other mammalian T lymphocytes at very low concentrations. Unlike traditional antigens, superantigens do not require processing by antigen-presenting cells, and the antigen-binding region on the outside of antigen-presenting cells combines with MHC II (histocompatibility complex) molecules and T cell Vβ regions to form a complex, Thereby a large number of T lymphocytes are stimulated to proliferate, which in turn leads to the release of a large number of cytokines and other effector molecules in vitro or in vivo. Because of the special biological activity and mechanism of action of...

AI Technical Summary

Problems solved by technology

However, since the function of enterotoxin C2 superantigen must depend on the combination with MHC II molecules in the immune system, this will inevitably lead to its possible combination with MHC II molecules from normal tissues or cells in the human body, thus affecting normal cells. It also produces certain toxic effects; in addition, because Staphylococcus aureus enterotoxin is a kind of bacterial exotoxin, it will produce certain symptoms of toxin syndrome (TSS) and food poisoning on the human body, and it is clinically manifested as vomiting, Diarrhea, and symptoms such as fever, thus limiting its clinical application and therapeutic effect

In the previous study, the binding ability of MHCII was changed, but it was found that with the decrease of toxicity, its tumor inhibitory activity also decreased significantly, and the clinical application prospect is not great.

Images