Impact of Expanded Small Alkyl Binding Pocket by Triple Point Mutations on Substrate Specificity of Thermoanaerobacter ethanolicus Secondary Alcohol Dehydrogenase.


Abstract

Site-directed mutagenesis was employed to generate five different triple point mutations in the double mutant (C295A/I86A) of Thermoanaerobacter ethanolicus alcohol dehydrogenase (TeSADH) by computer-aided modeling with the aim of widening the small alkyl binding pocket. TeSADH engineering enables the enzyme to accept sterically hindered substrates which could not be accepted by the wild-type enzyme. The underline in the mutations highlights the additional point mutation on the double mutant TeSADH introduced in this work. The catalytic efficiency (kcat/KM) of the M151A/C295A/I86A triple TeSADH mutant for acetophenone increased about 4.8-fold higher than that of the double mutant. A 2.4-fold increase in conversion of 3'-methylacetophenone to (R)-1-(3-methylphenyl)-ethanol with a yield of 87% was obtained by using V115A/C295A/I86A mutant in asymmetric reduction. The A85G/C295A/I86A mutant also produced (R)-1-(3-methylphenyl)-ethanol (1.7-fold) from 3'-methylacetophenone and (R)-1-(3-methoxyphenyl)ethanol (1.2-fold) from 3'-methoxyacetophenone, with improved yield. In terms of thermal stability, the M151A/C295A/I86A and V115A/C295A/I86A mutants significantly increased ΔT1/2 by +6.8°C and +2.4°C, respectively, with thermal deactivation constant (kd) close to the wild-type enzyme. The M151A/C295A/I86A mutant reacts optimally at 70 °C with almost 4 times more residual activity than the wild-type. Considering broad substrate tolerance and thermal stability together, it would be promising to produce (R)-1-(3-methylphenyl)-ethanol from 3'-methylacetophenone by V115A/C295A/I86A, and (R)-1-phenylethanol from acetophenone by M151A/C295A/I86A mutant, in large-scale bioreduction processes.

Submission Details

ID: ARyouSQr

Submitter: Shu-Ching Ou

Submission Date: March 25, 2019, 1:21 p.m.

Version: 1

Publication Details
Dwamena AK;Phillips RS;Kim CS,J Microbiol Biotechnol (2019) Impact of Expanded Small Alkyl Binding Pocket by Triple Point Mutations on Substrate Specificity of Thermoanaerobacter ethanolicus Secondary Alcohol Dehydrogenase. PMID:30609883
Additional Information

For V115A+C295A+I86A, A85G+C295A+I86A variants, protein concentration in the kinetic experiments is halved.

Structure view and single mutant data analysis

Study data

No weblogo for data of varying length.
Colors: D E R H K S T N Q A V I L M F Y W C G P
 

Data Distribution

Studies with similar sequences (approximate matches)

Correlation with other assays (exact sequence matches)


Relevant PDB Entries

Structure ID Release Date Resolution Structure Title
3FPC 2010-01-19 1.4 Chimera of alcohol dehydrogenase by exchange of the cofactor binding domain res 153-294 of T. brockii ADH by E. histolytica ADH
3FPL 2010-01-19 1.9 Chimera of alcohol dehydrogenase by exchange of the cofactor binding domain res 153-295 of C. beijerinckii ADH by T. brockii ADH
3FTN 2010-01-26 2.19 Q165E/S254K Double Mutant Chimera of alcohol dehydrogenase by exchange of the cofactor binding domain res 153-295 of T. brockii ADH by C. beijerinckii ADH
3FSR 2010-01-19 2.2 Chimera of alcohol dehydrogenase by exchange of the cofactor binding domain res 153-295 of T. brockii ADH by C. beijerinckii ADH
1YKF 1998-01-14 2.5 NADP-DEPENDENT ALCOHOL DEHYDROGENASE FROM THERMOANAEROBIUM BROCKII
2NVB 2007-11-13 2.8 Contribution of Pro275 to the Thermostability of the Alcohol Dehydrogenases (ADHs)
1BXZ 2000-02-18 2.99 CRYSTAL STRUCTURE OF A THERMOPHILIC ALCOHOL DEHYDROGENASE SUBSTRATE COMPLEX FROM THERMOANAEROBACTER BROCKII

Relevant UniProtKB Entries

Percent Identity Matching Chains Protein Accession Entry Name
400.0 A,B,C,D NADP-dependent isopropanol dehydrogenase P14941 ADH_THEBR