[Elucidation of functionally active domains in molecules of protective antigen bacillus anthracis's toxin]

Limited proteolysis has established that the protective antigen (PA) molecule consists of four functional-active domains. So, the shielding domain borrows an area in the linear structure of the PA molecule with NH2 of the end up to Lys 166 and plays a conducting role in the proteolytic activation of PA. The associative domain, engaging in the area Arg 167-Met266, plays a key role in the interaction with LF or EF at self-assembly toxic complexes LT or ET. The stabilizing domain borrows in the linear structure of the PA molecule are with Gly351 up to Met434. On the one hand, this area promotes formation with LF conformationally steady toxic complex's, and, on the other, takes a direct participation in the formation of a hydrophobic channel by which the molecule LF or EF enters the target cell. The receptor domain, representing a COOH-terminal area, starting from Leu663 amino acid, begins to interact with specific receptors on the macrophages and thus delivers the toxic complex to the target cell. It has been found that in the molecule of lethal factor there are 3 functionally active domains located in the linear structure of the molecule as follows: the associative domain borrows an area from Lys39 up to Met242, stabilizing and effector domains occupy areas from Leu517 to Lys614 and from that point to Lys COOH-terminal amino acid.