Deciphering the Structural Basis of High Thermostability of Dehalogenase from Psychrophilic Bacterium <i>Marinobacter</i> sp. ELB17

• Main Authors: Lukas Chrast, Katsiaryna Tratsiak, Joan Planas-Iglesias, Lukas Daniel, Tatyana Prudnikova, Jan Brezovsky, David Bednar, Ivana Kuta Smatanova, Radka Chaloupkova, Jiri Damborsky
• Format: Article
• Language: English
• Published: MDPI AG 2019-10-01
• Series: Microorganisms
• Subjects: haloalkane dehalogenase; thermostability; psychrophile; access tunnel; dimer; catalytic pentad; enantiselectivity
• Online Access: https://www.mdpi.com/2076-2607/7/11/498

Haloalkane dehalogenases are enzymes with a broad application potential in biocatalysis, bioremediation, biosensing and cell imaging. The new haloalkane dehalogenase DmxA originating from the psychrophilic bacterium <i>Marinobacter</i> sp. ELB17 surprisingly possesses the highest thermal stability (apparent melting temperature <i>T</i>_m,app = 65.9 &#176;C) of all biochemically characterized wild type haloalkane dehalogenases belonging to subfamily II. The enzyme was successfully expressed and its crystal structure was solved at 1.45 &#197; resolution. DmxA structure contains several features distinct from known members of haloalkane dehalogenase family: (i) a unique composition of catalytic residues; (ii) a dimeric state mediated by a disulfide bridge; and (iii) narrow tunnels connecting the enzyme active site with the surrounding solvent. The importance of narrow tunnels in such paradoxically high stability of DmxA enzyme was confirmed by computational protein design and mutagenesis experiments.