A Further Biochemical Characterization of DrPLL the Thermophilic Lactonase from Deinococcus radiodurans
Abstract:Recently, the cloning of the ORF Dr0930 from Deinococcus radiodurans displaying, as primary activity, a lactonase activity and a promiscuous phosphotriesterase activity was reported. The crystal structure of the resulting recombinant enzyme has been solved, and many mutants have been generated in order to increase the phosphotriesterase activity, with the aim to reach the level of activity of the related pPTE from Pseudomonas diminuta. In this paper we report an additional biochemical characterization of DrPLL and show that this enzyme has an optimal temperature for catalysis of 85 °C and possesses promiscuous carboxylesterase, phophodiesterase and thioesterase activities which were not previously described. A metal analysis was performed on the purified protein by inductively coupled plasma mass spectrometry (ICP-MS ELAN DRC-e), which confirmed the presence of Ni2+ as a main metal in the recombinant protein. Surprisingly, the specificity constants (s=kcat/KM) for the pNP-decanoate and pNP-dodecanoate esters were only one order of magnitude lower than that for the lactone substrate thio-buthyl-γ-butyric-lactone (TBBL), and the KM value for TBBL was more than ten-fold higher than those for the esters. We named this enzyme DrPLL, based on its structural and biochemical features it belongs to the Phosphotriesterase Like Lactonase group, a small protein family belonging to the amidohydrolase superfamily.
Document Type: Research Article
Publication date: 2013-01-01
More about this publication?
- Protein & Peptide Letters publishes short papers in all important aspects of protein and peptide research, including structural studies, recombinant expression, function, synthesis, enzymology, immunology, molecular modeling, drug design etc. Manuscripts must have a significant element of novelty, timeliness and urgency that merit rapid publication. Reports of crystallisation, and preliminary structure determinations of biologically important proteins are acceptable. Purely theoretical papers are also acceptable provided they provide new insight into the principles of protein/peptide structure and function.