4jdr

Publication Abstract from PubMed

Multi-faceted structural approaches were undertaken to investigate interaction of the E2 component with E3 and E1 components from the E. coli pyruvate dehydrogenase multienzyme complex (PDHc), as a representative of PDHc's from Gram-negative bacteria. The crystal structure of E3 at 2.5A 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: (1) greatly diminish PDHc activity; (2) affect interactions with E3 and E1 components; and (3) affect reductive acetylation of E2. Since no crystal structure is available for any complete E2, peptide-specific H/D exchange mass spectrometry was used to identify loci of interactions between 3 lipoyl E2 and E3. Two peptides from the PSBD, including R129, and three peptides from E3 displayed statistically significant reductions in deuterium uptake resulting from interactions 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 R129, as well as revealing other electrostatic interactions likely stabilizing this complex.

Insight to the Interaction of the E2 Core with the Peripheral Components in the Escherichia coli Pyruvate Dehydrogenase complex via Multifaceted Structural Approaches.,Chandrasekhar K, Wang J, Arjunan P, Sax M, Park YH, Nemeria NS, Kumaran S, Song J, Jordan F, Furey W J Biol Chem. 2013 Apr 11. PMID:23580650^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.