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Free keywords:
Catalytic Domain
Cryoelectron Microscopy
Dihydrolipoyllysine-Residue Acetyltransferase/chemistry/metabolism
Escherichia coli Proteins/*chemistry/isolation & purification/metabolism
Hydrophobic and Hydrophilic Interactions
Lysine/analogs & derivatives/chemistry/metabolism
Models, Molecular
Protein Domains
Pyruvate Dehydrogenase Complex/*chemistry/isolation & purification/*metabolism
Thioctic Acid/analogs & derivatives/chemistry/metabolism
Abstract:
The pyruvate dehydrogenase complex (PDHc) links glycolysis to the citric acid cycle by converting pyruvate into acetyl-coenzyme A. PDHc encompasses three enzymatically active subunits, namely pyruvate dehydrogenase, dihydrolipoyl transacetylase, and dihydrolipoyl dehydrogenase. Dihydrolipoyl transacetylase is a multidomain protein comprising a varying number of lipoyl domains, a peripheral subunit-binding domain, and a catalytic domain. It forms the structural core of the complex, provides binding sites for the other enzymes, and shuffles reaction intermediates between the active sites through covalently bound lipoyl domains. The molecular mechanism by which this shuttling occurs has remained elusive. Here, we report a cryo-EM reconstruction of the native E. coli dihydrolipoyl transacetylase core in a resting state. This structure provides molecular details of the assembly of the core and reveals how the lipoyl domains interact with the core at the active site.
