Solution structure and dynamics of the lipoic acid-bearing domain of human mitochondrial branched-chain alpha-keto acid dehydrogenase complex

J Biol Chem. 2002 May 3;277(18):15865-73. doi: 10.1074/jbc.M110952200. Epub 2002 Feb 11.

Abstract

The lipoyl-bearing domain (LBD) of the transacylase (E2) subunit of the branched-chain alpha-keto acid dehydrogenase complex plays a central role in substrate channeling in this mitochondrial multienzyme complex. We have employed multidimensional heteronuclear NMR techniques to determine the structure and dynamics of the LBD of the human branched-chain alpha-keto acid dehydrogenase complex (hbLBD). Similar to LBD from other members of the alpha-keto acid dehydrogenase family, the solution structure of hbLBD is a flattened beta-barrel formed by two four-stranded antiparallel beta-sheets. The lipoyl Lys(44) residue resides at the tip of a beta-hairpin comprising a sharp type I beta-turn and the two connecting beta-strands 4 and 5. A prominent V-shaped groove formed by a surface loop, L1, connecting beta 1- and beta 2-strands and the lipoyl lysine beta-hairpin constitutes the functional pocket. We further applied reduced spectral density functions formalism to extract dynamic information of hbLBD from (15)N-T(1), (15)N-T(2), and ((1)H-(15)N) nuclear Overhauser effect data obtained at 600 MHz. The results showed that residues surrounding the lipoyl lysine region comprising the L1 loop and the Lys(44) beta-turn are highly flexible, whereas beta-sheet S1 appears to display a slow conformational exchange process.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)
  • Binding Sites
  • Cloning, Molecular
  • Escherichia coli
  • Humans
  • Ketone Oxidoreductases / chemistry*
  • Ketone Oxidoreductases / metabolism
  • Kinetics
  • Mitochondria / enzymology*
  • Models, Molecular
  • Multienzyme Complexes / chemistry*
  • Multienzyme Complexes / metabolism
  • Protein Conformation
  • Protein Structure, Secondary
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Solutions
  • Thioctic Acid / metabolism*

Substances

  • Multienzyme Complexes
  • Recombinant Proteins
  • Solutions
  • Thioctic Acid
  • Ketone Oxidoreductases
  • 3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)

Associated data

  • PDB/1K8M
  • PDB/1K8O