Crystal structure of the complex between 4-hydroxybutyrate CoA-transferase from Clostridium aminobutyricum and CoA
- PDF / 775,937 Bytes
- 10 Pages / 595.276 x 790.866 pts Page_size
- 11 Downloads / 176 Views
ORIGINAL PAPER
Crystal structure of the complex between 4-hydroxybutyrate CoA-transferase from Clostridium aminobutyricum and CoA Sofia Macieira • Jin Zhang • Wolfgang Buckel Albrecht Messerschmidt
•
Received: 10 March 2011 / Revised: 27 June 2011 / Accepted: 8 July 2011 / Published online: 11 August 2011 Ó Springer-Verlag 2011
Abstract Clostridium aminobutyricum ferments 4-aminobutyrate (c-aminobutyrate, GABA) to ammonia, acetate and butyrate via 4-hydroxybutyrate that is activated to the CoAthioester catalyzed by 4-hydroxybutyrate CoA-transferase. Then, 4-hydroxybutyryl-CoA is dehydrated to crotonyl-CoA, which disproportionates to butyryl-CoA and acetyl-CoA. Cocrystallization of the CoA-transferase with the alternate substrate butyryl-CoA yielded crystals with non-covalently bound CoA and two water molecules at the active site. Most likely, butyryl-CoA reacted with the active site Glu238 to CoA and the mixed anhydride, which slowly hydrolyzed during crystallization. The structure of the CoA is similar but less stretched than that of the CoA-moiety of the covalent enzyme-CoA-thioester in 4-hydroxybutyrate CoA-transferase from Shewanella oneidensis. In contrast to the structures of the apo-enzyme and enzyme-CoA-thioester, the structure
Communicated by Theo Hansen. Sofia Macieira and Jin Zhang contributed equally. Coordinates of the structure described in this paper have been deposited in the Protein Data Bank with code 3QDQ. S. Macieira A. Messerschmidt (&) Department of Proteomics and Signal Transduction, Max-Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany e-mail: [email protected] J. Zhang W. Buckel Laboratory for Microbiology, Department of Biology, Philipps Universita¨t, 35032 Marburg, Germany W. Buckel Max-Planck Institute of Terrestrial Microbiology, Karl-von Frisch-Str, 35043 Marburg, Germany
described here has a closed conformation, probably caused by a flip of the active site loop (residues 215–219). During turnover, the closed conformation may protect the anhydride intermediate from hydrolysis and CoA from dissociation from the enzyme. Hence, one catalytic cycle changes conformation of the enzyme four times: free enzyme—open conformation, CoA? anhydride 1—closed, enzymeCoA-thioester—open, CoA ? anhydride-2—closed, free enzyme—open. Keywords Coenzyme A Crystal structure Enzyme complex
Introduction CoA-transferases (CoATs, EC 2.8.3.) catalyze the activation of carboxylic acids to CoA-thioesters without the expense of ATP. They transfer the CoAS- moiety from a CoA-thioester to a carboxylate to form to new CoA-thioester, whereby an oxygen atom from the carboxylate migrates in the reverse direction. These enzymes have been subdivided into three families with different catalytic mechanisms (Heider 2001). Family I forms a CoA-thioester intermediate with an active site glutamyl residue and follows ping-pong kinetics. Family II catalyzes the transfer of the thiolate moiety of acetyl-S-acyl carrier protein or acetyl-CoA directly to citrate or (S)-citramalate witho
Data Loading...
