Transcarboxylase 12S crystal structure: hexamer assembly and substrate binding to a multienzyme core.
Transcarboxylase from Propionibacterium shermanii is a 1.2 MDa multienzyme complex that couples two carboxylation reactions, transferring CO(2)(-) from methylmalonyl-CoA to pyruvate, yielding propionyl-CoA and oxaloacetate. The 1.9 A resolution crystal structure of the central 12S hexameric core, which catalyzes the first carboxylation reaction, has been solved bound to its substrate methylmalonyl-CoA. Overall, the structure reveals two stacked trimers related by 2-fold symmetry, and a domain duplication in the monomer. In the active site, the labile carboxylate group of methylmalonyl-CoA is stabilized by interaction with the N-termini of two alpha-helices. The 12S domains are structurally similar to the crotonase/isomerase superfamily, although only domain 1 of each 12S monomer binds ligand. The 12S reaction is similar to that of human propionyl-CoA carboxylase, whose beta-subunit has 50% sequence identity with 12S. A homology model of the propionyl-CoA carboxylase beta-subunit, based on this 12S crystal structure, provides new insight into the propionyl-CoA carboxylase mechanism, its oligomeric structure and the molecular basis of mutations responsible for enzyme deficiency in propionic acidemia.
Hall
Pamela R
PR
Department of Molecular Cardiology and Center for Structural Biology, Lerner Research Institute, Cleveland Clinic Foundation, OH 44195, USA.
Wang
Yan-Fei
YF
Rivera-Hainaj
Rosa E
RE
Zheng
Xiaojing
X
Pustai-Carey
Marianne
M
Carey
Paul R
PR
Yee
Vivien C
VC
D000214:Acyl Coenzyme A / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D002104:Cadmium / Q000378:metabolism; D019878:Carboxyl and Carbamoyl Transferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009097:Multienzyme Complexes; D011485:Protein Binding; D017510:Protein Folding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment
D000214:Acyl Coenzyme A; D001426:Bacterial Proteins; D009097:Multienzyme Complexes; D021122:Protein Subunits; D002104:Cadmium; C015357:methylmalonyl-coenzyme A; D019878:Carboxyl and Carbamoyl Transferases; C021580:Methylmalonyl-CoA carboxytransferase