1rr2
From Proteopedia
Propionibacterium shermanii transcarboxylase 5S subunit bound to 2-ketobutyric acid
Structural highlights
Function5S_PROFR The 5S subunit specifically catalyzes the transfer of the carboxyl group from biotin of the 1.3S subunit to pyruvate to form oxaloacetate and 1.3S biotin. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedTranscarboxylase is a 1.2 million Dalton (Da) multienzyme complex from Propionibacterium shermanii that couples two carboxylation reactions, transferring CO(2)(-) from methylmalonyl-CoA to pyruvate to yield propionyl-CoA and oxaloacetate. Crystal structures of the 5S metalloenzyme subunit, which catalyzes the second carboxylation reaction, have been solved in free form and bound to its substrate pyruvate, product oxaloacetate, or inhibitor 2-ketobutyrate. The structure reveals a dimer of beta(8)alpha(8) barrels with an active site cobalt ion coordinated by a carbamylated lysine, except in the oxaloacetate complex in which the product's carboxylate group serves as a ligand instead. 5S and human pyruvate carboxylase (PC), an enzyme crucial to gluconeogenesis, catalyze similar reactions. A 5S-based homology model of the PC carboxyltransferase domain indicates a conserved mechanism and explains the molecular basis of mutations in lactic acidemia. PC disease mutations reproduced in 5S result in a similar decrease in carboxyltransferase activity and crystal structures with altered active sites. Transcarboxylase 5S structures: assembly and catalytic mechanism of a multienzyme complex subunit.,Hall PR, Zheng R, Antony L, Pusztai-Carey M, Carey PR, Yee VC EMBO J. 2004 Sep 15;23(18):3621-31. Epub 2004 Aug 26. PMID:15329673[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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