Mechanism of the quorum-quenching lactonase (AiiA) from Bacillus thuringiensis. 1. Product-bound structures

作者：Liu Dali; Momb Jessica; Thomas Pei W; Moulin Aaron; Petsko Gregory A; Fast Walter^*; Ringe Dagmar

来源：Biochemistry, 2008, 47(29): 7706-7714.

DOI：10.1021/bi800368y

Enzymes capable of hydrolyzing N-acyl-L-homoserine lactones (AHLs) used in some bacterial quorum-sensing pathways are of considerable interest for their ability to block undesirable phenotypes. Most known AHL hydrolases that catalyze ring opening (AHL lactonases) are members of the metallo-beta-lactamase enzyme superfamily and rely on a dinuclear zinc site for catalysis and stability. Here we report the three-dimensional structures of three product complexes formed with the AHL lactonase from Bacillus thuringiensis. Structures of the lactonase bound with two different concentrations of the ring-opened product of N-hexanoyl-L-homoserine lactone are determined at 0.95 and 1.4 angstrom resolution and exhibit different product configurations. A structure of the ring opened product of the non-natural N-hexanoyl-L-homocysteine thiolactone at 1.3 angstrom resolution is also determined. On the basis of these product-bound structures, a substrate-binding model is presented that differs from previous proposals. Additionally, the proximity of the product to active-site residues and observed changes in protein conformation and metal coordination provide insight into the catalytic mechanism of this quorum-quenching metalloenzyme.

• 出版日期2008-7-22