Heat-labile enterotoxin A subunit mutant R192G (LT-A(R192G))

Heat-labile enterotoxin A subunit mutant R192G is a genetically engineered variant of the A subunit from the heat-labile enterotoxin (LT) of enterotoxigenic Escherichia coli (ETEC). This mutation (arginine to glycine at position 192) disrupts proteolytic processing critical for activation of the ADP-ribosyltransferase function, resulting in dramatic reduction or loss of enterotoxicity while preserving strong mucosal adjuvant properties. The mutant is frequently used in vaccine research and development, often termed “mLT” or “LT(R192G)”, as it activates the mucosal immune system without causing diarrhea or other toxic effects typical of the wild-type LT. This allows safer administration as an adjuvant in oral, sublingual, or mucosal vaccines against various infectious diseases, including ETEC and other pathogens[1][5][4]. The molecule itself is not a classic drug target, but its immunologic modulation properties have made it a focus of vaccine adjuvant research and a proof-of-concept model for detoxifying bacterial AB toxins.

Other names

Heat-labile enterotoxin A mutant R192GLT-A R192Gmutant heat-labile enterotoxin A subunitmLT (sometimes, though mLT can refer broadly to mutant LT forms)LT(R192G)

For wild-type: Enzymatic ADP-ribosylation of Gsα in host cells, resulting in constitutive activation of adenylate cyclase and elevated cAMP leading to fluid secretion (secretory diarrhea)[3][1]. For the R192G mutant: Mutation at Arg192 disrupts processing and dramatically reduces enzymatic activity, rendering the protein non-toxic (loss of enterotoxicity), but retaining its ability to function as a mucosal vaccine adjuvant through immunostimulatory mechanisms[1][5].