TY - JOUR

T1 - Single Point Mutation Abolishes Water Capture in Germacradien-4-ol Synthase

AU - González Requena, Víctor

AU - Srivastava, Prabhakar L

AU - Miller, David J

AU - Allemann, Rudolf K

N1 - © 2024 The Authors. ChemBioChem published by Wiley-VCH GmbH.

PY - 2024/12/2

Y1 - 2024/12/2

N2 - The high-fidelity sesquiterpene cyclase (-)-germacradien-4-ol synthase (GdolS) converts farnesyl diphosphate into the macrocyclic alcohol (-)-germacradien-4-ol. Site-directed mutagenesis was used to decipher the role of key residues in the water control mechanism. Replacement of Ala176, located in the G1/2 helix, with non-polar aliphatic residues of increasing size (valine, leucine, isoleucine and methionine) resulted in the accumulation of the non-hydroxylated products germacrene A and germacrene D. In contrast, hydroxylation was maintained when the polar residues threonine, glutamine or aspartate replaced Ala176. Additionally, although a contribution of His150 to the nucleophilic water addition could be ruled out, the imidazole ring of His150 appears to assist carbocation stabilisation. The results presented here shed light on how hydroxylating sesquiterpene synthases can be engineered to design modified sesquiterpene synthases to reduce the need for further steps in the biocatalytic production of oxygenated sesquiterpenoids.

AB - The high-fidelity sesquiterpene cyclase (-)-germacradien-4-ol synthase (GdolS) converts farnesyl diphosphate into the macrocyclic alcohol (-)-germacradien-4-ol. Site-directed mutagenesis was used to decipher the role of key residues in the water control mechanism. Replacement of Ala176, located in the G1/2 helix, with non-polar aliphatic residues of increasing size (valine, leucine, isoleucine and methionine) resulted in the accumulation of the non-hydroxylated products germacrene A and germacrene D. In contrast, hydroxylation was maintained when the polar residues threonine, glutamine or aspartate replaced Ala176. Additionally, although a contribution of His150 to the nucleophilic water addition could be ruled out, the imidazole ring of His150 appears to assist carbocation stabilisation. The results presented here shed light on how hydroxylating sesquiterpene synthases can be engineered to design modified sesquiterpene synthases to reduce the need for further steps in the biocatalytic production of oxygenated sesquiterpenoids.

KW - Water/chemistry

KW - Point Mutation

KW - Mutagenesis, Site-Directed

KW - Sesquiterpenes, Germacrane/metabolism

U2 - 10.1002/cbic.202400290

DO - 10.1002/cbic.202400290

M3 - Article

C2 - 39031755

VL - 25

SP - e202400290

JO - ChemBioChem

JF - ChemBioChem

SN - 1439-7633

IS - 23

ER -