Cryo-EM analysis reveals new insights into the mechanism of action of pyruvate carboxylase.
Pyruvate carboxylase (PC) is a conserved multifunctional enzyme linked to important metabolic diseases. PC homotetramer is arranged in two layers with two opposing monomers per layer. Cryo-EM explores the conformational variability of PC in the presence of different substrates. The results demonstrate that the biotin-carboxyl carrier protein (BCCP) domain localizes near the biotin carboxylase (BC) domain of its own monomer and travels to the carboxyltransferase (CT) domain of the opposite monomer. All density maps show noticeable conformational differences between layers, mainly for the BCCP and BC domains. This asymmetry may be indicative of a coordination mechanism where monomers from different layers catalyze the BC and CT reactions consecutively. A conformational change of the PC tetramerization (PT) domain suggests a new functional role in communication. A long-range communication pathway between subunits in different layers, via interacting PT-PT and BC-BC domains, may be responsible for the cooperativity of PC from Staphylococcus aureus.
Structural Biology Unit, Center for Cooperative Research in Biosciences bioGUNE, 48160 Derio, Spain.
Gorka
G
Lasso
Linda P C
LP
Yu
David
D
Gil
Song
S
Xiang
Liang
L
Tong
Mikel
M
Valle
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D019731:Carbon-Nitrogen Ligases / Q000737:chemistry / Q000378:metabolism; D019878:Carboxyl and Carbamoyl Transferases / Q000737:chemistry / Q000378:metabolism; D020134:Catalytic Domain; D020285:Cryoelectron Microscopy; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D011485:Protein Binding; D017510:Protein Folding; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D011766:Pyruvate Carboxylase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D013211:Staphylococcus aureus / Q000201:enzymology; D013379:Substrate Specificity
D001426:Bacterial Proteins; D011994:Recombinant Proteins; D019878:Carboxyl and Carbamoyl Transferases; D019731:Carbon-Nitrogen Ligases; C019791:biotin carboxylase; D011766:Pyruvate Carboxylase