title: Structure of the pyruvate dehydrogenase multienzyme complex E1 component from Escherichia coli at 1.85 A resolution.
abstract: The crystal structure of the recombinant thiamin diphosphate-dependent E1 component from the Escherichia coli pyruvate dehydrogenase multienzyme complex (PDHc) has been determined at a resolution of 1.85 A. The E. coli PDHc E1 component E1p is a homodimeric enzyme and crystallizes with an intact dimer in an asymmetric unit. Each E1p subunit consists of three domains: N-terminal, middle, and C-terminal, with all having alpha/beta folds. The functional dimer contains two catalytic centers located at the interface between subunits. The ThDP cofactors are bound in the "V" conformation in clefts between the two subunits (binding involves the N-terminal and middle domains), and there is a common ThDP binding fold. The cofactors are completely buried, as only the C2 atoms are accessible from solution through the active site clefts. Significant structural differences are observed between individual domains of E1p relative to heterotetrameric multienzyme complex E1 components operating on branched chain substrates. These differences may be responsible for reported alternative E1p binding modes to E2 components within the respective complexes. This paper represents the first structural example of a functional pyruvate dehydrogenase E1p component from any species. It also provides the first representative example for the entire family of homodimeric (alpha2) E1 multienzyme complex components, and should serve as a model for this class of enzymes.
authors.affiliation: Biocrystallography Laboratory, Veterans Affairs Medical Center, P. O. Box 12055, University Drive C, Pittsburgh, Pennsylvania 15240, USA.
authors.forename: Palaniappa
authors.initials: P
authors.lastname: Arjunan
authors.forename: Natalia
authors.initials: N
authors.lastname: Nemeria
authors.forename: Andrew
authors.initials: A
authors.lastname: Brunskill
authors.forename: Krishnamoorthy
authors.initials: K
authors.lastname: Chandrasekhar
authors.forename: Martin
authors.initials: M
authors.lastname: Sax
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.forename: Frank
authors.initials: F
authors.lastname: Jordan
authors.forename: John R
authors.initials: JR
authors.lastname: Guest
authors.forename: William
authors.initials: W
authors.lastname: Furey
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli / Q000201:enzymology*; D008274:Magnesium / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011768:Pyruvate Dehydrogenase Complex / Q000737:chemistry* / Q000378:metabolism; D012997:Solvents; D013835:Thiamine Pyrophosphate / Q000737:chemistry / Q000378:metabolism; D014867:Water
chemical_list: D011768:Pyruvate Dehydrogenase Complex; D012997:Solvents; C453599:pyruvate dehydrogenase multienzyme complex E1; D014867:Water; D008274:Magnesium; D013835:Thiamine Pyrophosphate