Red Rover, Red Rover, Send BCCP Over!: Coordinating Catalysis in Pyruvate Carboxylase

Cells exist in a state of continuous metabolic flux. The Krebs cycle, a central metabolic hub in the cell, is responsible for supplying precursors for the synthesis of amino acids, nucleotides, and compounds required for energy transfer. During periods of increased metabolic flux, metabolites in the Krebs cycle become depleted and must be replenished. Pyruvate carboxylase (PC), a multifunctional enzyme, replenishes the Krebs cycle by catalyzing the conversion of pyruvate to oxaloacetate, a Krebs cycle intermediate. The Shorewood SMART Team (Students Modeling A Research Topic) created a model of PC using 3D printing technology. PC contains four distinct domains: biotin carboxylase (BC), central allosteric, carboxyltransferase (CT), and biotin carboxyl carrier protein (BCCP). The overall reaction is initiated by BCCP‐biotin carboxylation in the BC domain. BCCP‐carboxybiotin physically translocates to the CT domain to transfer its carboxyl group to pyruvate. The active site of the CT domain undergoes a reconfiguration upon pyruvate binding to accommodate the docking of BCCP‐carboxybiotin for pyruvate carboxylation. With the rise in antibiotic resistance, understanding how PC functions may provide a target in developing new antibiotics, whereby the new drug would eliminate critical metabolic activity, thus killing the bacteria. Supported by a grant from the NIH‐CTSA UL1RR031973.