Receptor-directed chimeric toxins created by sortase-mediated protein fusion.

ABSTRACT: Chimeric protein toxins that act selectively on cells expressing a designated receptor may serve as investigational probes and/or antitumor agents. Here, we report use of the enzyme sortase A (SrtA) to create four chimeric toxins designed to selectively kill cells bearing the tumor marker HER2. We first expressed and purified: (i) a receptor recognition-deficient form of diphtheria toxin that lacks its receptor-binding domain and (ii) a mutated, receptor-binding-deficient form of anthrax-protective antigen. Both proteins carried at the C terminus the sortase recognition sequence LPETGG and a H₆ affinity tag. Each toxin protein was mixed with SrtA plus either of two HER2-recognition proteins--a single-chain antibody fragment or an Affibody--both carrying an N-terminal G₅ tag. With wild-type

SUBMITTER: McCluskey AJ 

PROVIDER: S-EPMC3795991 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature