This model describes the TCA cycle 2-oxoglutarate system E2 component, dihydrolipoamide succinyltransferase. It is closely related to the pyruvate dehydrogenase E2 component, dihydrolipoamide acetyltransferase. The seed for this model includes mitochondrial and Gram-negative bacterial forms. Mycobacterial candidates are highly derived, differ in having and extra copy of the lipoyl-binding domain at the N-terminus. They score below the trusted cutoff, but above the noise cutoff and above all examples of dihydrolipoamide acetyltransferase. [Energy metabolism, TCA cycle]