The key role of E418 carboxyl group in the formation of Nt.BspD6I nickase active site: Structural and functional properties of Nt.BspD6I E418A mutant.

ABSTRACT

The mutated nickase Nt.BspD6I E418A has been obtained by site-directed mutagenesis. The purified protein has been crystallized, and its spatial structure has been determined at 2.45 Å resolution. An analysis of the crystal structures of the wild-type and mutated nickase have shown that the elimination of a carboxyl group due to the E418A mutation initiates marked conformational changes in both the N-terminal recognition domain and the C-terminal catalytic domain of nickase and insignificantly affects its linker domain. This is supported by changes in the functional properties of mutated nickase an increase in the oligomerization capacity in the presence of a substrate, a reduction in the capacity to bind a substrate, and complete loss of catalytic activity.