Sequential 1H and 15N nuclear magnetic resonance assignments and secondary structure of the lipoyl domain of the 2-oxoglutarate dehydrogenase complex from Azotobacter vinelandii. Evidence for high structural similarity with the lipoyl domain of the pyruvate dehydrogenase complex.
A 79-amino-acid polypeptide, corresponding to the lipoyl domain of the succinyltransferase component of the 2-oxoglutarate dehydrogenase multienzyme complex from Azotobacter vinelandii, has been sub-cloned and produced in Escherichia coli. Complete sequential 1H and 15N resonance assignments for the lipoyl domain have been obtained by using homo- and hetero-nuclear NMR spectroscopy. Two antiparallel beta-sheets of four strands each were identified from characteristic NOE connectivities and 3JHN alpha values. The lipoyl-lysine residue is found in a type-I turn connecting two beta-strands. The secondary structure of the lipoyl domain very much resembles the secondary solution structure of the N-terminal lipoyl domain of the A. vinelandii pyruvate dehydrogenase complex, despite the sequence identity of 25%. A detailed comparison of the NMR-derived parameters of both lipoyl domains, i.e. chemical shifts, NH-exchange rates, NOEs, and 3JHN alpha values suggests a high structural similarity in solution between the two lipoyl domains. Preliminary tertiary-structure calculations confirm that these lipoyl domains have very similar overall folds. The observed specificity of the 2-oxo acid dehydrogenase components of both complexes for these lipoyl domains is discussed in this respect.
Berg
A
A
Department of Biochemistry, Agricultural University, Wageningen, The Netherlands.
Smits
O
O
de Kok
A
A
Vervoort
J
J
D000595:Amino Acid Sequence; D016948:Azotobacter vinelandii / Q000201:enzymology*; D003001:Cloning, Molecular; D007655:Ketoglutarate Dehydrogenase Complex / Q000737:chemistry* / Q000235:genetics; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009587:Nitrogen Isotopes; D017433:Protein Structure, Secondary; D011522:Protons; D011768:Pyruvate Dehydrogenase Complex / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid
D009587:Nitrogen Isotopes; D011522:Protons; D011768:Pyruvate Dehydrogenase Complex; D007655:Ketoglutarate Dehydrogenase Complex