Change search
Link to record
Permanent link

Direct link
BETA
Gustafsson, Camilla
Publications (1 of 1) Show all publications
Gustafsson, C., Vassiliev, S., Kürten, C., Syrén, P.-O. & Brinck, T. (2017). MD Simulations Reveal Complex Water Paths in Squalene–Hopene Cyclase: Tunnel-Obstructing Mutations Increase the Flow of Water in the Active Site. ACS Omega, 2(11), 8495-8506
Open this publication in new window or tab >>MD Simulations Reveal Complex Water Paths in Squalene–Hopene Cyclase: Tunnel-Obstructing Mutations Increase the Flow of Water in the Active Site
Show others...
2017 (English)In: ACS Omega, ISSN 2470-1343, Vol. 2, no 11, p. 8495-8506Article in journal (Refereed) Published
Abstract [en]

Squalene–hopene cyclase catalyzes the cyclization of squalene to hopanoids. A previous study has identified a network of tunnels in the protein, where water molecules have been indicated to move. Blocking these tunnels by site-directed mutagenesis was found to change the activation entropy of the catalytic reaction from positive to negative with a concomitant lowering of the activation enthalpy. As a consequence, some variants are faster and others are slower than the wild type (wt) in vitro under optimal reaction conditions for the wt. In this study, molecular dynamics (MD) simulations have been performed for the wt and the variants to investigate how the mutations affect the protein structure and the water flow in the enzyme, hypothetically influencing the activation parameters. Interestingly, the tunnel-obstructing variants are associated with an increased flow of water in the active site, particularly close to the catalytic residue Asp376. MD simulations with the substrate present in the active site indicate that the distance for the rate-determining proton transfer between Asp376 and the substrate is longer in the tunnel-obstructing protein variants than in the wt. On the basis of the previous experimental results and the current MD results, we propose that the tunnel-obstructing variants, at least partly, could operate by a different catalytic mechanism, where the proton transfer may have contributions from a Grotthuss-like mechanism.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2017
National Category
Biocatalysis and Enzyme Technology Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:kth:diva-234939 (URN)10.1021/acsomega.7b01084 (DOI)000418744100113 ()
Funder
Science for Life Laboratory - a national resource center for high-throughput molecular bioscience
Note

QC 20180914

Available from: 2018-09-13 Created: 2018-09-13 Last updated: 2018-09-18Bibliographically approved
Organisations

Search in DiVA

Show all publications