3rqc

Publication Abstract from PubMed

The dihydrolipoyl acyl-transferase (E2) enzyme forms the structural and catalytic core of the tripartite 2-oxoacid dehydrogenase multienzyme complexes of the central metabolic pathways. Although this family of multienzyme complexes shares a common architecture, their E2 cores form homo-trimers that, depending on the source, further associate into either octahedral (24-mer) or icosahedral (60-mer) assemblies, as predicted by the principles of quasi-equivalence. In the crystal structure of the E2 core from Thermoplasma acidophilum, a thermophilic archaeon, the homo-trimers assemble into a unique 42-mer oblate spheroid. Analytical equilibrium centrifugation and small-angle X-ray scattering analyses confirm that this catalytically active 1.08 MDa assembly exists as a single species in solution, forming a hollow spheroid with a maximum diameter of 220 A. In this paper we show that a monodisperse macromolecular assembly, built from identical subunits in non-identical environments, forms an irregular protein shell via non-equivalent interactions. This unusually irregular protein shell, combining cubic and dodecahedral geometrical elements, expands on the concept of quasi-equivalence as a basis for understanding macromolecular assemblies by showing that cubic point group symmetry is not a physical requirement in multienzyme assembly. These results extend our basic knowledge of protein assembly and greatly expand the number of possibilities to manipulate self-assembling biological complexes to be utilized in innovative nanotechnology applications.

The catalytic core of an archaeal 2-oxoacid dehydrogenase multienzyme complex is a 42-mer protein assembly.,Marrott NL, Marshall JJ, Svergun DI, Crennell SJ, Hough DW, Danson MJ, van den Elsen JM FEBS J. 2012 Mar;279(5):713-23. doi: 10.1111/j.1742-4658.2011.08461.x. Epub 2012 , Jan 19. PMID:22188654^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.