title: Structural and functional characterization of a novel α/β hydrolase from cariogenic pathogen Streptococcus mutans.
abstract: The protein Smu.1393c from Streptococcus mutans is annotated as a putative α/β hydrolase, but it has low sequence identity to the structure-known α/β hydrolases. Here we present the crystal structure of Smu.1393c at 2.0 Å resolution. Smu.1393c has a fully open alkaline substrate pocket, whose conformation is unique among other similar hydrolase structures. Three residues, Ser101, His251, and Glu125, were identified as the active center of Smu.1393c. By screening a series of artificial hydrolase substrates, we demonstrated Smu.1393c had low carboxylesterase activity towards short-chain carboxyl esters, which provided a clue for exploring the in vivo function of Smu.1393c.
authors.affiliation: State Key Laboratory of Protein and Plant Gene Research, and Biodynamic Optical Imaging Center (BIOPIC), School of Life Sciences, Peking University, Beijing, 100871, China.
authors.forename: Zixi
authors.initials: Z
authors.lastname: Wang
authors.forename: Lanfen
authors.initials: L
authors.lastname: Li
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Su
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000648:ultrastructure; D002265:Carboxylic Ester Hydrolases; D020134:Catalytic Domain; D003460:Crystallization; D018360:Crystallography, X-Ray; D006867:Hydrolases / Q000737:chemistry* / Q000648:ultrastructure*; D013295:Streptococcus mutans / Q000201:enzymology*
chemical_list: D001426:Bacterial Proteins; D006867:Hydrolases; D002265:Carboxylic Ester Hydrolases
keywords: Smu.1393c; X-ray crystallography; cap domain; carboxylesterase; catalytic triad