Chunlei Kong

Promiscuous esterase activities of the C-C hydrolases from Dyella ginsengisoli.

A C–C hydrolase gene (bphDLA-4) from strain Dyella ginsengisoli LA-4 was cloned and expressed in Escherichia coli BL21 (DE3). BphDLA-4 together with another hydrolase MfphALA-4, which derived from the same strain, possessed esterase activities. p-Nitrophenyl butyrate was the best substrate for both enzymes. BphDLA-4 had high catalytic efficiency to p-nitrophenyl benzoate, whereas MfphALA-4 had no activity. Homology modeling and docking studies demonstrated that the proper hydrogen bond interaction was important for the reactivity of specific substrate.

Genome Sequence of Dyella ginsengisoli Strain LA-4, an Efficient Degrader of Aromatic Compounds

ABSTRACT Dyella ginsengisoli strain LA-4 can efficiently degrade environmental pollutants such as biphenyl and azo dyes. Here, we present a 4.55-Mb draft genome sequence of strain LA-4, which may provide further insights into the molecular mechanism in environmental pollution remediation.

Catalytic performance and stability of C-C bond hydrolase BphD immobilized onto single-wall carbon nanotubes

Abstract Single-wall carbon nanotubes (SWCNTs) possess unique mechanical properties and extraordinary thermal conductivity, and were used as the matrix for immobilized biocatalysts. The C-C bond hydrolase BphD was immobilized on SWCNTs by physical adsorption and covalent bonding. The relative activity, stability, and reusability of the immobilized enzyme were investigated. BphD immobilized by physical adsorption retained 52.5% of the activity of free BphD, and BphD thermal stability and denaturant resistance were also improved. Covalently bound BphD exhibited the activity nearly the same as that of free BphD (99.7% of initial activity), but its stability showed no significant improvement over that of free BphD.

Tuning the substrate selectivity of meta-cleavage product hydrolase by domain swapping

Abstractmeta-Cleavage product (MCP) hydrolases can catalyze relatively low reactive carbon–carbon bond hydrolysis of products, which are derived from the meta-cleavage of catechols. The strict substrate selectivity of MCP hydrolases attracts an interest to understand the determinants of substrate specificity. Compared with conventional site-directed mutagenesis, domain swapping is an effective strategy to explore substrate specificity due to the large-scale reorganization of three-dimensional structure. In the present study, the hybrid MCP hydrolases BphDLidA and MfphALidD were constructed by exchanging the lid domain of two parental enzymes MfphA and BphD. The residues Gly130/Ala196 (MfphA) and Gly136/Ala211 (BphD) were selected as crossover points according to structural disruption score analysis and molecular dynamics simulations. It was shown that the hybrid enzymes exhibited similar substrate selectivity with the parent enzyme providing the lid domain. Docking studies suggested that the lid domain may play a key role in determining substrate specificity by reshaping the active pocket and modulating the orientation of the substrate.