1rqh
From Proteopedia
Propionibacterium shermanii transcarboxylase 5S subunit bound to pyruvic acid
Overview
Transcarboxylase 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.
About this Structure
1RQH is a Single protein structure of sequence from Propionibacterium freudenreichii subsp. shermanii. Full crystallographic information is available from OCA.
Reference
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 Page seeded by OCA on Sat May 3 07:47:41 2008
