How Does Surface Charge Engineering of Bacillus subtilis Lipase A Improve Ionic Liquid Resistance? Lessons Learned from Molecular Dynamics Simulations

ACS Sustainable Chemistry & Engineering, vol. 10, pp. 2689–2698

Abstract

Biocatalysis in ionic liquids (ILs) gained substantial interest due to solvent properties of the ILs, such as near-zero vapor pressure, high thermal stability, and wide tunability. Enzymes are often not catalytically active in ILs; therefore, understanding and improving enzyme resistance in ILs are essential to enable efficient biocatalysis in ionic liquids. Surface charge engineering has repeatedly been reported to enhance enzyme resistance toward ILs. However, the molecular knowledge about how substitutions to charged amino acids improve enzyme activity in an IL is far from being understood. Here, we report a comprehensive study to provide some principles of how surface charged amino acid substitutions (negatively and positively) strengthen the IL resistance of the Bacillus subtilis lipase A (BSLA) in [BMIM]Cl. Twenty typical BSLA substitutions (ten beneficial and ten nonbeneficial, obtained from the BSLA-SSM library) were studied by molecular dynamics (MD) simulations in the [BMIM]Cl system. The BSLA-IL interaction patterns were printed by analyzing several structural- and solvation-based observables. Lessons learned by analyzing the SSM library of BSLA comprise the following: (i) A general trend was found where both negatively and positively charged substitutions increased the essential water molecules locally at the substitution site, thereby contributing to the overall protein hydration shell. (ii) Electrostatic repulsion of both IL ions and the refined hydration shell are ultimately the two main drivers to enhanced IL resistance. The analysis of 20 BSLA substitutions and the identified common interactions reveals that surface charge engineering is very likely to be a general protein engineering strategy to enhance lipase/enzyme activity in ILs. Moreover, this study also suggests that MD is a valuable technique to screen for beneficial substitutions that repel/recruit surface solvation.

Authors 8

1. Subrata Pramanik Aachen Institute of Biotechnology

   Indian Institute of Technology Guwahati · RWTH Aachen University

   Affiliation as printed

   Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, Aachen 52074, Germany

   School of Health Science and Technology, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India

2. Haiyang Cui Aachen DWI - Leibniz Institute for Interactive Materials Institute of Biotechnology

   DWI – Leibniz Institute for Interactive Materials · RWTH Aachen University

   Affiliation as printed

   DWI-Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, Aachen 52074, Germany

   Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, Aachen 52074, Germany

3. Gaurao V. Dhoke Aachen Institute of Biotechnology

   RWTH Aachen University

   Affiliation as printed

   Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, Aachen 52074, Germany

4. Can Bora Yildiz Aachen Institute of Biotechnology

   RWTH Aachen University

   Affiliation as printed

   Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, Aachen 52074, Germany

5. Markus Vedder Aachen Institute of Biotechnology

   RWTH Aachen University

   Affiliation as printed

   Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, Aachen 52074, Germany

6. Karl‐Erich Jaeger

   Forschungszentrum Jülich · Heinrich Heine University Düsseldorf

   Affiliation as printed

   Institute of Bio- and Geosciences IBG 1: Biotechnology, Forschungszentrum Jülich GmbH, Wilhelm Johnen Strasse, Jülich 52426, Germany

   Institute of Molecular Enzyme Technology, Heinrich Heine University Düsseldorf, Wilhelm Johnen Strasse, Jülich 52426, Germany

7. Ulrich Schwaneberg corresponding Aachen DWI - Leibniz Institute for Interactive Materials Institute of Biotechnology

   DWI – Leibniz Institute for Interactive Materials · RWTH Aachen University

   Affiliation as printed

   DWI-Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, Aachen 52074, Germany

   Institute of Biotechnology, RWTH Aachen University, Worringerweg 3, Aachen 52074, Germany

8. Mehdi D. Davari corresponding

   Leibniz Institute of Plant Biochemistry

   Affiliation as printed

   Department of Bioorganic Chemistry, Leibniz Institute of Plant Biochemistry, Weinberg 3, 06120 Halle, Germany