1HQS

CRYSTAL STRUCTURE OF ISOCITRATE DEHYDROGENASE FROM BACILLUS SUBTILIS

Summary for 1HQS

• Entry DOI: 10.2210/pdb1hqs/pdb
• Descriptor: ISOCITRATE DEHYDROGENASE, CITRIC ACID, S-1,2-PROPANEDIOL, ... (5 entities in total)
• Functional Keywords: glyoxylate bypass, bsidh, tricarboxylic acid cycle, oxidoreductase, protein phosphorylation, nadp
• Biological source: Bacillus subtilis
• Total number of polymer chains: 2
• Total formula weight: 94006.24

Authors

Singh, S.K.,Matsuno, K.,LaPorte, D.C.,Banaszak, L.J. (deposition date: 2000-12-19, release date: 2001-07-25, Last modification date: 2023-08-09)

Primary citation

Singh, S.K.,Matsuno, K.,LaPorte, D.C.,Banaszak, L.J.
Crystal structure of Bacillus subtilis isocitrate dehydrogenase at 1.55 A. Insights into the nature of substrate specificity exhibited by Escherichia coli isocitrate dehydrogenase kinase/phosphatase.
J.Biol.Chem., 276:26154-26163, 2001

PubMed Abstract: Isocitrate dehydrogenase from Bacillus subtilis (BsIDH) is a member of a family of metal-dependent decarboxylating dehydrogenases. Its crystal structure was solved to 1.55 A and detailed comparisons with the homologue from Escherichia coli (EcIDH), the founding member of this family, were made. Although the two IDHs are structurally similar, there are three notable differences between them. First, a mostly nonpolar beta-strand and two connecting loops in the small domain of EcIDH are replaced by two polar alpha-helices in BsIDH. Because of a 13-residue insert in this region of BsIDH, these helices protrude over the active site cleft of the opposing monomer. Second, a coil leading into this cleft, the so-called "phosphorylation" loop, is bent inward in the B. subtilis enzyme, narrowing the entrance to the active site from about 12 to 4 A. Third, although BsIDH is a homodimer, the two unique crystallographic subunits of BsIDH are not structurally identical. The two monomers appear to differ by a domain shift of the large domain relative to the small domain/clasp region, reminiscent of what has been observed in the open/closed conformations of EcIDH. In Escherichia coli, IDH is regulated by reversible phosphorylation by the bifunctional enzyme IDH kinase/phosphatase (IDH-K/P). The site of phosphorylation is Ser(113), which lies deep within the active site crevice. Structural differences between EcIDH and BsIDH may explain disparities in their abilities to act as substrates for IDH-K/P.

PubMed: 11290745
DOI: 10.1074/jbc.M101191200

Experimental method

X-RAY DIFFRACTION (1.55 Å)