title: Crystal structures of TM0549 and NE1324--two orthologs of E. coli AHAS isozyme III small regulatory subunit.
abstract: Crystal structures of two orthologs of the regulatory subunit of acetohydroxyacid synthase III (AHAS, EC 2.2.1.6) from Thermotoga maritima (TM0549) and Nitrosomonas europea (NE1324) were determined by single-wavelength anomalous diffraction methods with the use of selenomethionine derivatives at 2.3 A and 2.5 A, respectively. TM0549 and NE1324 share the same fold, and in both proteins the polypeptide chain contains two separate domains of a similar size. Each protein contains a C-terminal domain with ferredoxin-type fold and an N-terminal ACT domain, of which the latter is characteristic for several proteins involved in amino acid metabolism. The ferredoxin domain is stabilized by a calcium ion in the crystal structure of NE1324 and by a Mg(H2O)(6)2+ ion in TM0549. Both TM0549 and NE1324 form dimeric assemblies in the crystal lattice.
authors.affiliation: Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville 22908, USA.
authors.forename: Janusz J
authors.initials: JJ
authors.lastname: Petkowski
authors.forename: Maksymilian
authors.initials: M
authors.lastname: Chruszcz
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Zimmerman
authors.forename: Heping
authors.initials: H
authors.lastname: Zheng
authors.forename: Tatiana
authors.initials: T
authors.lastname: Skarina
authors.forename: Olena
authors.initials: O
authors.lastname: Onopriyenko
authors.forename: Marcin T
authors.initials: MT
authors.lastname: Cymborowski
authors.forename: Katarzyna D
authors.initials: KD
authors.lastname: Koclega
authors.forename: Alexei
authors.initials: A
authors.lastname: Savchenko
authors.forename: Aled
authors.initials: A
authors.lastname: Edwards
authors.forename: Wladek
authors.initials: W
authors.lastname: Minor
mesh_terms: D000095:Acetolactate Synthase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001120:Arginine / Q000737:chemistry / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D020124:Thermotoga maritima / Q000201:enzymology* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D007527:Isoenzymes; D001120:Arginine; D000095:Acetolactate Synthase; D002118:Calcium