title: Insight to the interaction of the dihydrolipoamide acetyltransferase (E2) core with the peripheral components in the Escherichia coli pyruvate dehydrogenase complex via multifaceted structural approaches.
abstract: Multifaceted structural approaches were undertaken to investigate interaction of the E2 component with E3 and E1 components from the Escherichia coli pyruvate dehydrogenase multienzyme complex (PDHc), as a representative of the PDHc from Gram-negative bacteria. The crystal structure of E3 at 2.5 Å resolution reveals similarity to other E3 structures and was an important starting point for understanding interaction surfaces between E3 and E2. Biochemical studies revealed that R129E-E2 and R150E-E2 substitutions in the peripheral subunit-binding domain (PSBD) of E2 greatly diminished PDHc activity, affected interactions with E3 and E1 components, and affected reductive acetylation of E2. Because crystal structures are unavailable for any complete E2-containing complexes, peptide-specific hydrogen/deuterium exchange mass spectrometry was used to identify loci of interactions between 3-lipoyl E2 and E3. Two peptides from the PSBD, including Arg-129, and three peptides from E3 displayed statistically significant reductions in deuterium uptake resulting from interaction between E3 and E2. Of the peptides identified on E3, two were from the catalytic site, and the third was from the interface domain, which for all known E3 structures is believed to interact with the PSBD. NMR clearly demonstrates that there is no change in the lipoyl domain structure on complexation with E3. This is the first instance where the entire wild-type E2 component was employed to understand interactions with E3. A model for PSBD-E3 binding was independently constructed and found to be consistent with the importance of Arg-129, as well as revealing other electrostatic interactions likely stabilizing this complex.
authors.affiliation: Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
authors.forename: Krishnamoorthy
authors.initials: K
authors.lastname: Chandrasekhar
authors.forename: Junjie
authors.initials: J
authors.lastname: Wang
authors.forename: Palaniappa
authors.initials: P
authors.lastname: Arjunan
authors.forename: Martin
authors.initials: M
authors.lastname: Sax
authors.forename: Yun-Hee
authors.initials: YH
authors.lastname: Park
authors.forename: Natalia S
authors.initials: NS
authors.lastname: Nemeria
authors.forename: Sowmini
authors.initials: S
authors.lastname: Kumaran
authors.forename: Jaeyoung
authors.initials: J
authors.lastname: Song
authors.forename: Frank
authors.initials: F
authors.lastname: Jordan
authors.forename: William
authors.initials: W
authors.lastname: Furey
mesh_terms: D019943:Amino Acid Substitution; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D051047:Dihydrolipoyllysine-Residue Acetyltransferase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D020125:Mutation, Missense; D020836:Protein Structure, Quaternary; D011768:Pyruvate Dehydrogenase Complex / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D011768:Pyruvate Dehydrogenase Complex; D051047:Dihydrolipoyllysine-Residue Acetyltransferase
keywords: Crystallography; Enzyme Structure; H/D Exchange MS; Lipoamide Dehydrogenase; NMR; Protein-Protein Interactions; Pyruvate Dehydrogenase Complex