National Center for
4MTU: Beta-alanyl-coa:ammonia Lyase From Clostridium Propionicum
High resolution crystal structure of Clostridium propionicum beta-alanyl-CoA:ammonia lyase, a new member of the "hot dog fold" protein superfamily
Proteins (2014) 82 p.2041-2053
Clostridium propionicum is the only organism known to ferment beta-alanine, a constituent of coenzyme A (CoA) and the phosphopantetheinyl prosthetic group of holo-acyl carrier protein. The first step in the fermentation is a CoA-transfer to beta-alanine. Subsequently, the resulting beta-alanyl-CoA is deaminated by the enzyme beta-alanyl-CoA:ammonia lyase (Acl) to reversibly form ammonia and acrylyl-CoA. We have determined the crystal structure of Acl in its apo-form at a resolution of 0.97 A as well as in complex with CoA at a resolution of 1.59 A. The structures reveal that the enyzme belongs to a superfamily of proteins exhibiting a so called "hot dog fold" which is characterized by a five-stranded antiparallel beta-sheet with a long alpha-helix packed against it. The functional unit of all "hot dog fold" proteins is a homodimer containing two equivalent substrate binding sites which are established by the dimer interface. In the case of Acl, three functional dimers combine to a homohexamer strongly resembling the homohexamer formed by YciA-like acyl-CoA thioesterases. Here, we propose an enzymatic mechanism based on the crystal structure of the Acl.CoA complex and molecular docking. Proteins 2014; 82:2041-2053. (c) 2014 Wiley Periodicals, Inc.