InterPro domain: IPR036230

This is the C-terminal regulatory (R) domain of alpha-isopropylmalate synthase, which catalyses the first committed step in the leucine biosynthetic pathway [ 1 ]. This domain, is an internally duplicated structure with a novel fold [ 2 ]. It comprises two similar units that are arranged such that the two helices pack together in the centre, crossing at an angle of 34 degrees, sandwiched between the two three-stranded, antiparallel beta-sheets. The overall domain is thus constructed as a beta-alpha-beta three-layer sandwich [ 2 ].

1. Crystal structure of LeuA from Mycobacterium tuberculosis, a key enzyme in leucine biosynthesis. Proc. Natl. Acad. Sci. U.S.A. 101, 8295-300