Structural basis for thermostability revealed through the identification and characterization of a highly thermostable phosphotriesterase-like lactonase from Geobacillus stearothermophilus

• Published in: Archives of biochemistry and biophysics 2009-08, Vol.488 (2), p.109-120
• Main Authors: Hawwa, Renda, Aikens, John, Turner, Robert J., Santarsiero, Bernard D., Mesecar, Andrew D.
• Format: Article
• Language: English
• Subjects: Activation energy; Amino Acid Sequence; Arrhenius; BASIC BIOLOGICAL SCIENCES; Binding Sites; Bioremediation; Carboxylic Ester Hydrolases - metabolism; Cloning, Molecular; Crystallization; Dimerization; Enzyme Stability; ENZYMES; Escherichia coli - genetics; Extremophile; GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; Genome, Bacterial; Geobacillus; Geobacillus stearothermophilus - enzymology; Geobacillus stearothermophilus - genetics; Hydrogen Bonding; Hydrolysis; Hydrophobic and Hydrophilic Interactions; INCUBATION; Kinetics; LACTONES; Models, Chemical; Models, Molecular; Molecular Sequence Data; Phosphoric Triester Hydrolases - chemistry; Phosphoric Triester Hydrolases - genetics; Phosphoric Triester Hydrolases - isolation & purification; Phosphoric Triester Hydrolases - metabolism; Phosphotriesterase-like lactonase; Plasmids - genetics; Promoter Regions, Genetic; Protein Binding; Protein Structure, Secondary; Sequence Homology, Amino Acid; Solubility; Substrate Specificity; Temperature; Thermal advantage score; Thermophile; Time Factors; Transformation, Bacterial; X-Rays
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1016/j.abb.2009.06.005

A new enzyme homologous to phosphotriesterase was identified from the bacterium Geobacillus stearothermophilus (GsP). This enzyme belongs to the amidohydrolase family and possesses the ability to hydrolyze both lactone and organophosphate (OP) compounds, making it a phosphotriesterase-like lactonase (PLL). GsP possesses higher OP-degrading activity than recently characterized PLLs, and it is extremely thermostable. GsP is active up to 100 °C with an energy of activation of 8.0 kcal/mol towards ethyl paraoxon, and it can withstand an incubation temperature of 60 °C for two days. In an attempt to understand the thermostability of PLLs, the X-ray structure of GsP was determined and compared to those of existing PLLs. Based upon a comparative analysis, a new thermal advantage score and plot was developed and reveals that a number of different factors contribute to the thermostability of PLLs.